Develop Reference

Concatenate string and list to create a list of paths [duplicate]

I would like to put an int into a string. This is what I am doing at the moment:
num = 40
plot.savefig('hanning40.pdf') #problem line
I have to run the program for several different numbers, so I'd like to do a loop. But inserting the variable like this doesn't work:
plot.savefig('hanning', num, '.pdf')
How do I insert a variable into a Python string?
See also
If you tried using + to concatenate a number with a string (or between strings, etc.) and got an error message, see How can I concatenate str and int objects?.
If you are trying to assemble a URL with variable data, do not use ordinary string formatting, because it is error-prone and more difficult than necessary. Specialized tools are available. See Add params to given URL in Python.
If you are trying to assemble a SQL query, do not use ordinary string formatting, because it is a major security risk. This is the cause of "SQL injection" which costs real companies huge amounts of money every year. See for example Python: best practice and securest way to connect to MySQL and execute queries for proper techniques.
If you just want to print (output) the string, you can prepare it this way first, or if you don't need the string for anything else, print each piece of the output individually using a single call to print. See How can I print multiple things (fixed text and/or variable values) on the same line, all at once? for details on both approaches.

Using f-strings:
plot.savefig(f'hanning{num}.pdf')
This was added in 3.6 and is the new preferred way.
Using str.format():
plot.savefig('hanning{0}.pdf'.format(num))
String concatenation:
plot.savefig('hanning' + str(num) + '.pdf')
Conversion Specifier:
plot.savefig('hanning%s.pdf' % num)
Using local variable names (neat trick):
plot.savefig('hanning%(num)s.pdf' % locals())
Using string.Template:
plot.savefig(string.Template('hanning${num}.pdf').substitute(locals()))
See also:
Fancier Output Formatting - The Python Tutorial
Python 3's f-Strings: An Improved String Formatting Syntax (Guide) - RealPython

With the introduction of formatted string literals ("f-strings" for short) in Python 3.6, it is now possible to write this with a briefer syntax:
>>> name = "Fred"
>>> f"He said his name is {name}."
'He said his name is Fred.'
With the example given in the question, it would look like this
plot.savefig(f'hanning{num}.pdf')

plot.savefig('hanning(%d).pdf' % num)
The % operator, when following a string, allows you to insert values into that string via format codes (the %d in this case). For more details, see the Python documentation:
printf-style String Formatting

You can use + as the normal string concatenation function as well as str().
"hello " + str(10) + " world" == "hello 10 world"

In general, you can create strings using:
stringExample = "someString " + str(someNumber)
print(stringExample)
plot.savefig(stringExample)

If you would want to put multiple values into the string you could make use of format
nums = [1,2,3]
plot.savefig('hanning{0}{1}{2}.pdf'.format(*nums))
Would result in the string hanning123.pdf. This can be done with any array.

Special cases
Depending on why variable data is being used with strings, the general-purpose approaches may not be appropriate.
If you need to prepare an SQL query
Do not use any of the usual techniques for assembling a string. Instead, use your SQL library's functionality for parameterized queries.
A query is code, so it should not be thought about like normal text. Using the library will make sure that any inserted text is properly escaped. If any part of the query could possibly come from outside the program in any way, that is an opportunity for a malevolent user to perform SQL injection. This is widely considered one of the important computer security problems, costing real companies huge amounts of money every year and causing problems for countless customers. Even if you think you know the data is "safe", there is no real upside to using any other approach.
The syntax will depend on the library you are using and is outside the scope of this answer.
If you need to prepare a URL query string
See Add params to given URL in Python. Do not do it yourself; there is no practical reason to make your life harder.
Writing to a file
While it's possible to prepare a string ahead of time, it may be simpler and more memory efficient to just write each piece of data with a separate .write call. Of course, non-strings will still need to be converted to string before writing, which may complicate the code. There is not a one-size-fits-all answer here, but choosing badly will generally not matter very much.
If you are simply calling print
The built-in print function accepts a variable number of arguments, and can take in any object and stringify it using str. Before trying string formatting, consider whether simply passing multiple arguments will do what you want. (You can also use the sep keyword argument to control spacing between the arguments.)
# display a filename, as an example
print('hanning', num, '.pdf', sep='')
Of course, there may be other reasons why it is useful for the program to assemble a string; so by all means do so where appropriate.
It's important to note that print is a special case. The only functions that work this way are ones that are explicitly written to work this way. For ordinary functions and methods, like input, or the savefig method of Matplotlib plots, we need to prepare a string ourselves.
Concatenation
Python supports using + between two strings, but not between strings and other types. To work around this, we need to convert other values to string explicitly: 'hanning' + str(num) + '.pdf'.
Template-based approaches
Most ways to solve the problem involve having some kind of "template" string that includes "placeholders" that show where information should be added, and then using some function or method to add the missing information.
f-strings
This is the recommended approach when possible. It looks like f'hanning{num}.pdf'. The names of variables to insert appear directly in the string. It is important to note that there is not actually such a thing as an "f-string"; it's not a separate type. Instead, Python will translate the code ahead of time:
>>> def example(num):
... return f'hanning{num}.pdf'
...
>>> import dis
>>> dis.dis(example)
2 0 LOAD_CONST 1 ('hanning')
2 LOAD_FAST 0 (num)
4 FORMAT_VALUE 0
6 LOAD_CONST 2 ('.pdf')
8 BUILD_STRING 3
10 RETURN_VALUE
Because it's a special syntax, it can access opcodes that aren't used in other approaches.
str.format
This is the recommended approach when f-strings aren't possible - mainly, because the template string needs to be prepared ahead of time and filled in later. It looks like 'hanning{}.pdf'.format(num), or 'hanning{num}.pdf'.format(num=num)'. Here, format is a method built in to strings, which can accept arguments either by position or keyword.
Particularly for str.format, it's useful to know that the built-in locals, globals and vars functions return dictionaries that map variable names to the contents of those variables. Thus, rather than something like '{a}{b}{c}'.format(a=a, b=b, c=c), we can use something like '{a}{b}{c}'.format(**locals()), unpacking the locals() dict.
str.format_map
This is a rare variation on .format. It looks like 'hanning{num}.pdf'.format_map({'num': num}). Rather than accepting keyword arguments, it accepts a single argument which is a mapping.
That probably doesn't sound very useful - after all, rather than 'hanning{num}.pdf'.format_map(my_dict), we could just as easily write 'hanning{num}.pdf'.format(**my_dict). However, this is useful for mappings that determine values on the fly, rather than ordinary dicts. In these cases, unpacking with ** might not work, because the set of keys might not be determined ahead of time; and trying to unpack keys based on the template is unwieldy (imagine: 'hanning{num}.pdf'.format(num=my_mapping[num]), with a separate argument for each placeholder).
string.Formatter
The string standard library module contains a rarely used Formatter class. Using it looks like string.Formatter().format('hanning{num}.pdf', num=num). The template string uses the same syntax again. This is obviously clunkier than just calling .format on the string; the motivation is to allow users to subclass Formatter to define a different syntax for the template string.
All of the above approaches use a common "formatting language" (although string.Formatter allows changing it); there are many other things that can be put inside the {}. Explaining how it works is beyond the scope of this answer; please consult the documentation. Do keep in mind that literal { and } characters need to be escaped by doubling them up. The syntax is presumably inspired by C#.
The % operator
This is a legacy way to solve the problem, inspired by C and C++. It has been discouraged for a long time, but is still supported. It looks like 'hanning%s.pdf' % num, for simple cases. As you'd expect, literal '%' symbols in the template need to be doubled up to escape them.
It has some issues:
It seems like the conversion specifier (the letter after the %) should match the type of whatever is being interpolated, but that's not actually the case. Instead, the value is converted to the specified type, and then to string from there. This isn't normally necessary; converting directly to string works most of the time, and converting to other types first doesn't help most of the rest of the time. So 's' is almost always used (unless you want the repr of the value, using 'r'). Despite that, the conversion specifier is a mandatory part of the syntax.
Tuples are handled specially: passing a tuple on the right-hand side is the way to provide multiple arguments. This is an ugly special case that's necessary because we aren't using function-call syntax. As a result, if you actually want to format a tuple into a single placeholder, it must be wrapped in a 1-tuple.
Other sequence types are not handled specially, and the different behaviour can be a gotcha.
string.Template
The string standard library module contains a rarely used Template class. Instances provide substitute and safe_substitute methods that work similarly to the built-in .format (safe_substitute will leave placeholders intact rather than raising an exception when the arguments don't match). This should also be considered a legacy approach to the problem.
It looks like string.Template('hanning$num.pdf').substitute(num=num), and is inspired by traditional Perl syntax. It's obviously clunkier than the .format approach, since a separate class has to be used before the method is available. Braces ({}) can be used optionally around the name of the variable, to avoid ambiguity. Similarly to the other methods, literal '$' in the template needs to be doubled up for escaping.

I had a need for an extended version of this: instead of embedding a single number in a string, I needed to generate a series of file names of the form 'file1.pdf', 'file2.pdf' etc. This is how it worked:
['file' + str(i) + '.pdf' for i in range(1,4)]

You can make dict and substitute variables in your string.
var = {"name": "Abdul Jalil", "age": 22}
temp_string = "My name is %(name)s. I am %(age)s years old." % var

Can I use variables in the prompt of the python raw_input function? [duplicate]

I would like to put an int into a string. This is what I am doing at the moment:
num = 40
plot.savefig('hanning40.pdf') #problem line
I have to run the program for several different numbers, so I'd like to do a loop. But inserting the variable like this doesn't work:
plot.savefig('hanning', num, '.pdf')
How do I insert a variable into a Python string?
See also
If you tried using + to concatenate a number with a string (or between strings, etc.) and got an error message, see How can I concatenate str and int objects?.
If you are trying to assemble a URL with variable data, do not use ordinary string formatting, because it is error-prone and more difficult than necessary. Specialized tools are available. See Add params to given URL in Python.
If you are trying to assemble a SQL query, do not use ordinary string formatting, because it is a major security risk. This is the cause of "SQL injection" which costs real companies huge amounts of money every year. See for example Python: best practice and securest way to connect to MySQL and execute queries for proper techniques.
If you just want to print (output) the string, you can prepare it this way first, or if you don't need the string for anything else, print each piece of the output individually using a single call to print. See How can I print multiple things (fixed text and/or variable values) on the same line, all at once? for details on both approaches.

Using f-strings:
plot.savefig(f'hanning{num}.pdf')
This was added in 3.6 and is the new preferred way.
Using str.format():
plot.savefig('hanning{0}.pdf'.format(num))
String concatenation:
plot.savefig('hanning' + str(num) + '.pdf')
Conversion Specifier:
plot.savefig('hanning%s.pdf' % num)
Using local variable names (neat trick):
plot.savefig('hanning%(num)s.pdf' % locals())
Using string.Template:
plot.savefig(string.Template('hanning${num}.pdf').substitute(locals()))
See also:
Fancier Output Formatting - The Python Tutorial
Python 3's f-Strings: An Improved String Formatting Syntax (Guide) - RealPython

With the introduction of formatted string literals ("f-strings" for short) in Python 3.6, it is now possible to write this with a briefer syntax:
>>> name = "Fred"
>>> f"He said his name is {name}."
'He said his name is Fred.'
With the example given in the question, it would look like this
plot.savefig(f'hanning{num}.pdf')

plot.savefig('hanning(%d).pdf' % num)
The % operator, when following a string, allows you to insert values into that string via format codes (the %d in this case). For more details, see the Python documentation:
printf-style String Formatting

You can use + as the normal string concatenation function as well as str().
"hello " + str(10) + " world" == "hello 10 world"

In general, you can create strings using:
stringExample = "someString " + str(someNumber)
print(stringExample)
plot.savefig(stringExample)

If you would want to put multiple values into the string you could make use of format
nums = [1,2,3]
plot.savefig('hanning{0}{1}{2}.pdf'.format(*nums))
Would result in the string hanning123.pdf. This can be done with any array.

Special cases
Depending on why variable data is being used with strings, the general-purpose approaches may not be appropriate.
If you need to prepare an SQL query
Do not use any of the usual techniques for assembling a string. Instead, use your SQL library's functionality for parameterized queries.
A query is code, so it should not be thought about like normal text. Using the library will make sure that any inserted text is properly escaped. If any part of the query could possibly come from outside the program in any way, that is an opportunity for a malevolent user to perform SQL injection. This is widely considered one of the important computer security problems, costing real companies huge amounts of money every year and causing problems for countless customers. Even if you think you know the data is "safe", there is no real upside to using any other approach.
The syntax will depend on the library you are using and is outside the scope of this answer.
If you need to prepare a URL query string
See Add params to given URL in Python. Do not do it yourself; there is no practical reason to make your life harder.
Writing to a file
While it's possible to prepare a string ahead of time, it may be simpler and more memory efficient to just write each piece of data with a separate .write call. Of course, non-strings will still need to be converted to string before writing, which may complicate the code. There is not a one-size-fits-all answer here, but choosing badly will generally not matter very much.
If you are simply calling print
The built-in print function accepts a variable number of arguments, and can take in any object and stringify it using str. Before trying string formatting, consider whether simply passing multiple arguments will do what you want. (You can also use the sep keyword argument to control spacing between the arguments.)
# display a filename, as an example
print('hanning', num, '.pdf', sep='')
Of course, there may be other reasons why it is useful for the program to assemble a string; so by all means do so where appropriate.
It's important to note that print is a special case. The only functions that work this way are ones that are explicitly written to work this way. For ordinary functions and methods, like input, or the savefig method of Matplotlib plots, we need to prepare a string ourselves.
Concatenation
Python supports using + between two strings, but not between strings and other types. To work around this, we need to convert other values to string explicitly: 'hanning' + str(num) + '.pdf'.
Template-based approaches
Most ways to solve the problem involve having some kind of "template" string that includes "placeholders" that show where information should be added, and then using some function or method to add the missing information.
f-strings
This is the recommended approach when possible. It looks like f'hanning{num}.pdf'. The names of variables to insert appear directly in the string. It is important to note that there is not actually such a thing as an "f-string"; it's not a separate type. Instead, Python will translate the code ahead of time:
>>> def example(num):
... return f'hanning{num}.pdf'
...
>>> import dis
>>> dis.dis(example)
2 0 LOAD_CONST 1 ('hanning')
2 LOAD_FAST 0 (num)
4 FORMAT_VALUE 0
6 LOAD_CONST 2 ('.pdf')
8 BUILD_STRING 3
10 RETURN_VALUE
Because it's a special syntax, it can access opcodes that aren't used in other approaches.
str.format
This is the recommended approach when f-strings aren't possible - mainly, because the template string needs to be prepared ahead of time and filled in later. It looks like 'hanning{}.pdf'.format(num), or 'hanning{num}.pdf'.format(num=num)'. Here, format is a method built in to strings, which can accept arguments either by position or keyword.
Particularly for str.format, it's useful to know that the built-in locals, globals and vars functions return dictionaries that map variable names to the contents of those variables. Thus, rather than something like '{a}{b}{c}'.format(a=a, b=b, c=c), we can use something like '{a}{b}{c}'.format(**locals()), unpacking the locals() dict.
str.format_map
This is a rare variation on .format. It looks like 'hanning{num}.pdf'.format_map({'num': num}). Rather than accepting keyword arguments, it accepts a single argument which is a mapping.
That probably doesn't sound very useful - after all, rather than 'hanning{num}.pdf'.format_map(my_dict), we could just as easily write 'hanning{num}.pdf'.format(**my_dict). However, this is useful for mappings that determine values on the fly, rather than ordinary dicts. In these cases, unpacking with ** might not work, because the set of keys might not be determined ahead of time; and trying to unpack keys based on the template is unwieldy (imagine: 'hanning{num}.pdf'.format(num=my_mapping[num]), with a separate argument for each placeholder).
string.Formatter
The string standard library module contains a rarely used Formatter class. Using it looks like string.Formatter().format('hanning{num}.pdf', num=num). The template string uses the same syntax again. This is obviously clunkier than just calling .format on the string; the motivation is to allow users to subclass Formatter to define a different syntax for the template string.
All of the above approaches use a common "formatting language" (although string.Formatter allows changing it); there are many other things that can be put inside the {}. Explaining how it works is beyond the scope of this answer; please consult the documentation. Do keep in mind that literal { and } characters need to be escaped by doubling them up. The syntax is presumably inspired by C#.
The % operator
This is a legacy way to solve the problem, inspired by C and C++. It has been discouraged for a long time, but is still supported. It looks like 'hanning%s.pdf' % num, for simple cases. As you'd expect, literal '%' symbols in the template need to be doubled up to escape them.
It has some issues:
It seems like the conversion specifier (the letter after the %) should match the type of whatever is being interpolated, but that's not actually the case. Instead, the value is converted to the specified type, and then to string from there. This isn't normally necessary; converting directly to string works most of the time, and converting to other types first doesn't help most of the rest of the time. So 's' is almost always used (unless you want the repr of the value, using 'r'). Despite that, the conversion specifier is a mandatory part of the syntax.
Tuples are handled specially: passing a tuple on the right-hand side is the way to provide multiple arguments. This is an ugly special case that's necessary because we aren't using function-call syntax. As a result, if you actually want to format a tuple into a single placeholder, it must be wrapped in a 1-tuple.
Other sequence types are not handled specially, and the different behaviour can be a gotcha.
string.Template
The string standard library module contains a rarely used Template class. Instances provide substitute and safe_substitute methods that work similarly to the built-in .format (safe_substitute will leave placeholders intact rather than raising an exception when the arguments don't match). This should also be considered a legacy approach to the problem.
It looks like string.Template('hanning$num.pdf').substitute(num=num), and is inspired by traditional Perl syntax. It's obviously clunkier than the .format approach, since a separate class has to be used before the method is available. Braces ({}) can be used optionally around the name of the variable, to avoid ambiguity. Similarly to the other methods, literal '$' in the template needs to be doubled up for escaping.

I had a need for an extended version of this: instead of embedding a single number in a string, I needed to generate a series of file names of the form 'file1.pdf', 'file2.pdf' etc. This is how it worked:
['file' + str(i) + '.pdf' for i in range(1,4)]

You can make dict and substitute variables in your string.
var = {"name": "Abdul Jalil", "age": 22}
temp_string = "My name is %(name)s. I am %(age)s years old." % var

Pretty-print Lisp using Python

Is there a way to pretty-print Lisp-style code string (in other words, a bunch of balanced parentheses and text within) in Python without re-inventing a wheel?

Short answer
I think a reasonable approach, if you can, is to generate Python lists or custom objects instead of strings and use the pprint module, as suggested by #saulspatz.
Long answer
The whole question look like an instance of an XY-problem. Why? because you are using Python (why not Lisp?) to manipulate strings (why not data-structures?) representing generated Lisp-style code, where Lisp-style is defined as "a bunch of parentheses and text within".
To the question "how to pretty-print?", I would thus respond "I wouldn't start from here!".
The best way to not reinvent the wheel in your case, apart from using existing wheels, is to stick to a simple output format.
But first of all all, why do you need to pretty-print? who will look at the resulting code?
Depending on the exact Lisp dialect you are using and the intended usage of the code, you could format your code very differently. Think about newlines, indentation and maximum width of your text, for example. The Common Lisp pretty-printer is particulary evolved and I doubt you want to have the same level of configurability.
If you used Lisp, a simple call to pprint would solve your problem, but you are using Python, so stick with the most reasonable output for the moment because pretty-printing is a can of worms.
If your code is intended for human readers, please:
don't put closing parenthesis on their own lines
don't vertically align open and close parenthesis
don't add spaces between opening parenthesis
This is ugly:
( * ( + 3 x )
(f
x
y
)
)
This is better:
(* (+ 3 x)
(f x y))
Or simply:
(* (+ 3 x) (f x y))
See here for more details.
But before printing, you have to parse your input string and make sure it is well-formed. Maybe you are sure it is well-formed, due to how you generate your forms, but I'd argue that the printer should ignore that and not make too many assumptions. If you passed the pretty-printer an AST represented by Python objects instead of just strings, this would be easier, as suggested in comments. You could build a data-structure or custom classes and use the pprint (python) module. That, as said above, seems to be the way to go in your case, if you can change how you generate your Lisp-style code.
With strings, you are supposed to handle any possible input and reject invalid ones.
This means checking that parenthesis and quotes are balanced (beware of escape characters), etc.
Actually, you don't need to really build an intermediate tree for printing (though it would probably help for other parts of your program), because Lisp-style code is made of forms that are easily nested and use a prefix notation: you can scan your input string from left-to-right and print as required when seeing parenthesis (open parenthesis: recurse; close parenthesis, return from recursion). When you first encounter an unescaped double-quote ", read until the next one ", ...
This, coupled with a simple printing method, could be sufficient for your needs.

I think the easiest method would be to use triple quotations. If you say:
print """
(((This is some lisp code))) """
It should work.
You can format your code any way you like within the triple quotes and it will come out the way you want it to.
Best of luck and happy coding!

I made this rudimentary pretty printer once for prettifying CLIPS, which is based on Lisp. Might help:
def clips_pprint(clips_str: str) -> str:
"""Pretty-prints a CLIPS string.
Indents a CLIPS string for easier visual confirmation during development
and verification.
Assumes the CLIPS string is valid CLIPS, i.e. braces are paired.
"""
LB = "("
RB = ")"
TAB = " " * 4
formatted_clips_str = ""
tab_count = 0
for c in clips_str:
if c == LB:
formatted_clips_str += os.linesep
for _i in range(tab_count):
formatted_clips_str += TAB
tab_count += 1
elif c == RB:
tab_count -= 1
formatted_clips_str += c
return formatted_clips_str.strip()

Split shell-like syntax in Haskell?

How can I split a string in shell-style syntax in Haskell? The equivalent in Python is shlex.split.
>>> shlex.split('''/nosuchconf "/this doesn't exist either" "yep"''')
['/nosuchconf', "/this doesn't exist either", 'yep']

I'm not sure what exactly you mean: are you wanting to get get all quoted sub-strings from a String? Note that unlike Python, etc. Haskell only has one set of quotes that indicate something is a String, namely "...".
Possibilities to consider:
The words and lines functions
The split package
Write a custom parser using polyparse, uu-parsinglib, parsec, etc.
It may be useful if you specified why you wanted such functionality: are you trying to parse existing shell scripts? Then language-sh might be of use. But you shouldn't be using such Strings internally in Haskell, and instead using [String] or something.

Safe expression parser in Python

How can I allow users to execute mathematical expressions in a safe way?
Do I need to write a full parser?
Is there something like ast.literal_eval(), but for expressions?

The examples provided with Pyparsing include several expression parsers:
https://github.com/pyparsing/pyparsing/blob/master/examples/fourFn.py is a conventional arithmetic infix notation parser/evaluator implementation using pyparsing. (Despite its name, this actually does 5-function arithmetic, plus several trig functions.)
https://github.com/pyparsing/pyparsing/blob/master/examples/simpleBool.py is a boolean infix notation parser/evaluator, using a pyparsing helper method operatorPrecedence, which simplifies the definition of infix operator notations.
https://github.com/pyparsing/pyparsing/blob/master/examples/simpleArith.py and https://github.com/pyparsing/pyparsing/blob/master/examples/eval_arith.py recast fourFn.py using operatorPrecedence. The first just parses and returns a parse tree; the second adds evaluation logic.
If you want a more pre-packaged solution, look at plusminus, a pyparsing-based extensible arithmetic parsing package.

What sort of expressions do you want? Variable assignment? Function evaluation?
SymPy aims to become a full-fledged Python CAS.

Few weeks ago I did similar thing, but for logical expressions (or, and, not, comparisons, parentheses etc.). I did this using Ply parser. I have created simple lexer and parser. Parser generated AST tree that was later use to perform calculations. Doing this in that way allow you to fully control what user enter, because only expressions that are compatible with grammar will be parsed.

Yes. Even if there were an equivalent of ast.literal_eval() for expressions, a Python expression can be lots of things other than just a pure mathematical expression, for example an arbitrary function call.
It wouldn't surprise me if there's already a good mathematical expression parser/evaluator available out there in some open-source module, but if not, it's pretty easy to write one of your own.

maths functions will consist of numeric and punctuation characters, possible 'E' or 'e' if you allow scientific notation for rational numbers, and the only (other) legal use of alpha characters will be if you allow/provide specific maths functions (e.g. stddev). So, should be trivial to run along the string for alpha characters and check the next little bit isn't suspicious, then simply eval the string in a try/except block.
Re the comments this reply has received... I agree this approach is playing with fire. Still, that doesn't mean it can't be done safely. I'm new to python (< 2 months), so may not know the workarounds to which this is vulnerable (and of course a new Python version could always render the code unsafe in the future), but - for what little it's worth (mainly my own amusement) - here's my crack at it:
def evalMaths(s):
i = 0
while i < len(s):
while s[i].isalpha() and i < len(s):
idn += s[i]
i += 1
if (idn and idn != 'e' and idn != 'abs' and idn != 'round'):
raise Exception("you naughty boy: don't " + repr(idn))
else:
i += 1
return eval(s)
I would be very interested to hear if/how it can be circumvented... (^_^) BTW / I know you can call functions like abs2783 or _983 - if they existed, but they won't. I mean something practical.
In fact, if anyone can do so, I'll create a question with 200 bounty and accept their answer.