Related
I have some code like:
def example(parameter):
global str
str = str(parameter)
print(str)
example(1)
example(2)
The first call to example works, but then the second time around I get an error like:
Traceback (most recent call last):
File "test.py", line 7, in <module>
example(2)
File "test.py", line 3, in example
str = str(parameter)
TypeError: 'str' object is not callable
Why does this happen, and how can I fix it?
If you are in an interactive session and encountered a problem like this, and you want to fix the problem without restarting the interpreter, see How to restore a builtin that I overwrote by accident?.
Where the code says:
global str
str = str(parameter)
You are redefining what str() means. str is the built-in Python name of the string type, and you don't want to change it.
Use a different name for the local variable, and remove the global statement.
Note that if you used code like this at the Python REPL, then the assignment to the global str will persist until you do something about it. You can restart the interpreter, or del str. The latter works because str is not actually a defined global variable by default - instead, it's normally found in a fallback (the builtins standard library module, which is specially imported at startup and given the global name __builtins__).
While not in your code, another hard-to-spot error is when the % character is missing in an attempt of string formatting:
"foo %s bar %s coffee"("blah","asdf")
but it should be:
"foo %s bar %s coffee"%("blah","asdf")
The missing % would result in the same TypeError: 'str' object is not callable.
In my case I had a class that had a method and a string property of the same name, I was trying to call the method but was getting the string property.
Note that TypeError: 'str' object is not callable means only that there is an attempt to call (i.e., use function-call syntax) a string (i.e., any name that previously had a string assigned to it). Using any other built-in method as variable name can cause the exact same error message.
You can get this error if you have variable str and trying to call str() function.
Whenever that happens, just issue the following ( it was also posted above)
>>> del str
That should fix it.
Another case of this: Messing with the __repr__ function of an object where a format() call fails non-transparently.
In our case, we used a #property decorator on the __repr__ and passed that object to a format(). The #property decorator causes the __repr__ object to be turned into a string, which then results in the str object is not callable error.
Check your input parameters, and make sure you don't have one named type. If so then you will have a clash and get this error.
str = 'Hello World String'
print(str(10)+' Good day!!')
Even I faced this issue with the above code as we are shadowing str() function.
Solution is:
string1 = 'Hello World String'
print(str(10)+' Good day!!')
I had the same error. In my case wasn't because of a variable named str. But because I named a function with a str parameter and the variable the same.
same_name = same_name(var_name: str)
I run it in a loop. The first time it run ok. The second time I got this error. Renaming the variable to a name different from the function name fixed this. So I think it's because Python once associate a function name in a scope, the second time tries to associate the left part (same_name =) as a call to the function and detects that the str parameter is not present, so it's missing, then it throws that error.
This error can also occur as a result of trying to call a property (as though it were a function):
class Example:
#property
def value():
return 'test'
e = Example()
print(e.value()) # should just be `e.value` to get the string
This problem can be caused by code like:
"Foo" ("Bar" if bar else "Baz")
You can concatenate string literals by putting them next to each other, like "Foo" "Bar". However, because of the open parenthesis, the code was interpreted as an attempt to call the string "Foo" as if it were a function.
it could be also you are trying to index in the wrong way:
a = 'apple'
a(3) ===> 'str' object is not callable
a[3] = l
it is recommended not to use str int list etc.. as variable names, even though python will allow it.
this is because it might create such accidents when trying to access reserved keywords that are named the same
This error could also occur with code like:
class Shape:
def __init__(self, colour):
self.colour = colour
def colour(self):
print("colour:", self.colour)
myShape = Shape("pink")
myShape.colour()
In the __init__ method, we assign an attribute colour, which has the same name as the method colour. When we later attempt to call the method, the instance's attribute is looked up instead. myShape.colour is the string "pink", which is not callable.
To fix this, change either the method name or the variable name.
I also got this error.
For me it was just a typo:
I wrote:
driver.find_element_by_id("swal2-content").text()
while it should have been:
driver.find_element_by_id("swal2-content").text
In my case, I had a Class with a method in it. The method did not have 'self' as the first parameter and the error was being thrown when I made a call to the method. Once I added 'self,' to the method's parameter list, it was fine.
FWIW I just hit this on a slightly different use case. I scoured and scoured my code looking for where I might've used a 'str' variable, but could not find it. I started to suspect that maybe one of the modules I imported was the culprit... but alas, it was a missing '%' character in a formatted print statement.
Here's an example:
x=5
y=6
print("x as a string is: %s. y as a string is: %s" (str(x) , str(y)) )
This will result in the output:
TypeError: 'str' object is not callable
The correction is:
x=5
y=6
print("x as a string is: %s. y as a string is: %s" % (str(x) , str(y)) )
Resulting in our expected output:
x as a string is: 5. y as a string is: 6
It also give same error if math library not imported,
import math
I realize this is not a runtime warning, but PyCharm gave me this similarly-worded IDE warning:
if hasattr(w, 'to_json'):
return w.to_json()
# warning, 'str' object is not callable
This was because the IDE assumed w.to_json was a string. The solution was to add a callable() check:
if hasattr(w, 'to_json') and callable(w.to_json):
return w.to_json()
Then the warning went away. This same check may also prevent the runtime exception in the original question.
I explain:
I would like to know how I can pass method or functions as arguments.
For example, in Python will be:
from MyFile import MyClass
MyClass().my_method_click(function) # without parentheses
In this example, in Python you send the functions or method without
parentheses, if I do:
from MyFile import MyClass
MyClass().my_method_click(function()) # with parentheses
I call the function but don't send it.
In Ruby, when you call a method or function, you can do it with or
without parentheses.
if I do this in Ruby:
require_relative "MyClass"
MyClass.new.my_method_click(function) # without parentheses
Just call it without send it.
Of course, is for a Button, that when I click it, run this operation.
How I can do it in Ruby??
Thanks!
Basically, you want to pass a runnable block of code. I haven't looked into Python yet, but I am sure it supports closures as well.
Anyhow, in Ruby, a "general" way of passing a runnable code is to use blocks (lambdas and procs).
function = lambda { # your code }
MyClass.new.my_method_click(function)
# or a shorter way
MyClass.new.my_method_click(-> { # your code })
# to run a block
def my_method_click(&block)
#you can either `yield` from your receiving method
yield
# or call `.call` method on your lambda/proc instance
block.call
end
You can also get an instance of your class' method or create a new method one using Method.new. But, you'd end up dealing with bindings and binding to the correct instance types, etc. So, it's much easier with Lambdas and Procs.
I am trying to call a function from a string in Python as explained in
Calling a function of a module from a string with the function's name in Python.
Unfortunately, this doesn't work, and the Python interpreter throws an error:
TypeError: 'str' object is not callable
def current(self, t):
if self.iMode == None:
return self.i
else:
return getattr(self, 'iMode')(t)
The error refers to the last line. iMode has been set to sinx(t), that has been declared in the class.
Can anyone help me please?
From the error message it is obvious that your attribute was set to 'sinx(t)' (the string literal).
You should set it the function reference sinx instead, which is a callable.
However, as zhangyangu already said, in you example using getattr() is not needed. Maybe you really want to use a parameter (string reference) instead of the literal 'iMode'?
From the error, your iMode is a string. The iMode is not a method. There must be something wrong with your declaration. And in the class you can use self.iMode, no need to use getattr.
I think you may look for the function like eval.
I have some code like:
def example(parameter):
global str
str = str(parameter)
print(str)
example(1)
example(2)
The first call to example works, but then the second time around I get an error like:
Traceback (most recent call last):
File "test.py", line 7, in <module>
example(2)
File "test.py", line 3, in example
str = str(parameter)
TypeError: 'str' object is not callable
Why does this happen, and how can I fix it?
If you are in an interactive session and encountered a problem like this, and you want to fix the problem without restarting the interpreter, see How to restore a builtin that I overwrote by accident?.
Where the code says:
global str
str = str(parameter)
You are redefining what str() means. str is the built-in Python name of the string type, and you don't want to change it.
Use a different name for the local variable, and remove the global statement.
Note that if you used code like this at the Python REPL, then the assignment to the global str will persist until you do something about it. You can restart the interpreter, or del str. The latter works because str is not actually a defined global variable by default - instead, it's normally found in a fallback (the builtins standard library module, which is specially imported at startup and given the global name __builtins__).
While not in your code, another hard-to-spot error is when the % character is missing in an attempt of string formatting:
"foo %s bar %s coffee"("blah","asdf")
but it should be:
"foo %s bar %s coffee"%("blah","asdf")
The missing % would result in the same TypeError: 'str' object is not callable.
In my case I had a class that had a method and a string property of the same name, I was trying to call the method but was getting the string property.
Note that TypeError: 'str' object is not callable means only that there is an attempt to call (i.e., use function-call syntax) a string (i.e., any name that previously had a string assigned to it). Using any other built-in method as variable name can cause the exact same error message.
You can get this error if you have variable str and trying to call str() function.
Whenever that happens, just issue the following ( it was also posted above)
>>> del str
That should fix it.
Another case of this: Messing with the __repr__ function of an object where a format() call fails non-transparently.
In our case, we used a #property decorator on the __repr__ and passed that object to a format(). The #property decorator causes the __repr__ object to be turned into a string, which then results in the str object is not callable error.
Check your input parameters, and make sure you don't have one named type. If so then you will have a clash and get this error.
str = 'Hello World String'
print(str(10)+' Good day!!')
Even I faced this issue with the above code as we are shadowing str() function.
Solution is:
string1 = 'Hello World String'
print(str(10)+' Good day!!')
I had the same error. In my case wasn't because of a variable named str. But because I named a function with a str parameter and the variable the same.
same_name = same_name(var_name: str)
I run it in a loop. The first time it run ok. The second time I got this error. Renaming the variable to a name different from the function name fixed this. So I think it's because Python once associate a function name in a scope, the second time tries to associate the left part (same_name =) as a call to the function and detects that the str parameter is not present, so it's missing, then it throws that error.
This error can also occur as a result of trying to call a property (as though it were a function):
class Example:
#property
def value():
return 'test'
e = Example()
print(e.value()) # should just be `e.value` to get the string
This problem can be caused by code like:
"Foo" ("Bar" if bar else "Baz")
You can concatenate string literals by putting them next to each other, like "Foo" "Bar". However, because of the open parenthesis, the code was interpreted as an attempt to call the string "Foo" as if it were a function.
it could be also you are trying to index in the wrong way:
a = 'apple'
a(3) ===> 'str' object is not callable
a[3] = l
it is recommended not to use str int list etc.. as variable names, even though python will allow it.
this is because it might create such accidents when trying to access reserved keywords that are named the same
This error could also occur with code like:
class Shape:
def __init__(self, colour):
self.colour = colour
def colour(self):
print("colour:", self.colour)
myShape = Shape("pink")
myShape.colour()
In the __init__ method, we assign an attribute colour, which has the same name as the method colour. When we later attempt to call the method, the instance's attribute is looked up instead. myShape.colour is the string "pink", which is not callable.
To fix this, change either the method name or the variable name.
I also got this error.
For me it was just a typo:
I wrote:
driver.find_element_by_id("swal2-content").text()
while it should have been:
driver.find_element_by_id("swal2-content").text
In my case, I had a Class with a method in it. The method did not have 'self' as the first parameter and the error was being thrown when I made a call to the method. Once I added 'self,' to the method's parameter list, it was fine.
FWIW I just hit this on a slightly different use case. I scoured and scoured my code looking for where I might've used a 'str' variable, but could not find it. I started to suspect that maybe one of the modules I imported was the culprit... but alas, it was a missing '%' character in a formatted print statement.
Here's an example:
x=5
y=6
print("x as a string is: %s. y as a string is: %s" (str(x) , str(y)) )
This will result in the output:
TypeError: 'str' object is not callable
The correction is:
x=5
y=6
print("x as a string is: %s. y as a string is: %s" % (str(x) , str(y)) )
Resulting in our expected output:
x as a string is: 5. y as a string is: 6
It also give same error if math library not imported,
import math
I realize this is not a runtime warning, but PyCharm gave me this similarly-worded IDE warning:
if hasattr(w, 'to_json'):
return w.to_json()
# warning, 'str' object is not callable
This was because the IDE assumed w.to_json was a string. The solution was to add a callable() check:
if hasattr(w, 'to_json') and callable(w.to_json):
return w.to_json()
Then the warning went away. This same check may also prevent the runtime exception in the original question.
I have a function that is supposed to take a string, append things to it where necessary, and return the result.
My natural inclination is to just return the result, which involved string concatenation, and if it failed, let the exception float up to the caller. However, this function has a default value, which I just return unmodified.
My question is: What if someone passed something unexpected to the method, and it returns something the user doesn't expect? The method should fail, but how to enforce that?
It's not necessary to do so, but if you want you can have your method raise a TypeError if you know that the object is of a type that you cannot handle. One reason to do this is to help people to understand why the method call is failing and to give them some help fixing it, rather than giving them obscure error from the internals of your function.
Some methods in the standard library do this:
>>> [] + 1
Traceback (most recent call last):
File "", line 1, in
TypeError: can only concatenate list (not "int") to list
You can use decorators for this kind of thing, you can see an example here.
But forcing parameters to be of a specific type isn't very pythonic.
Python works under the assumption that we are all intelligent adults that read the documentation. If you still want to do it, you should not assert the actual type, but rather just catch the exception when the argument does not support the operations you need, like that:
def foo(arg):
try:
return arg + "asdf"
except TypeError:
return arg
What does the default value have to do with it? Are you saying you want to return the default value in the case where the caller doesn't pass a str? In that case:
def yourFunc( foo ):
try:
return foo + " some stuff"
except TypeError:
return "default stuff"
Space_C0wb0y has the right answer if you want to return the arg unmodified if it's not a string, and there's also the option of making an attempt to convert something to a string:
def yourFunc2( bar ):
return str(bar) + " some stuff"
Which will work with a lot of different types.