exec in a function - Printable Version

exec in a function - Printable Version

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exec in a function - paul18fr - Apr-18-2021

Hi

I'm modifying a code by moving an "exec" inside a function creating an error; I wrote a small code highlighting what I'm facing.

What I'm missing and what is the correct programming ?

Thanks

What I'm missing

Sentence = "World is "

print("without using a function")
Add0 = 'beautifull'
exec("New0 = Sentence + '%s'" %Add0)
print("\t- Complete sentence 0 = {}".format(New0))

print("\nUsing a function")
def Complete(Part):
    Add = 'beautifull'
    exec("New = Part + '%s'" %Add)
    print("\t- Complete sentence 1 = {}".format(New))
    print("\t- Complete sentence 2 = %s" %(New))
    
Complete(Sentence)

RE: exec in a function - Yoriz - Apr-18-2021

You should include the error in your post

Error:
NameError: name 'New' is not defined

New is not the same as New0

RE: exec in a function - paul18fr - Apr-18-2021

(Apr-18-2021, 07:48 PM)Yoriz Wrote: You should include the error in your post

you're right, I'll do next time

I'm trying to understand why outside the function exec works (with New0) but not inside (with New that has no relation with New0); I'm missing things but I've not understood what so far

RE: exec in a function - Yoriz - Apr-18-2021

Sorry, i didn't notice the exec("New = Part + '%s'" %Add).

See this link

Sentence = "World is "
 
print("without using a function")
Add0 = 'beautifull'
exec("New0 = Sentence + '%s'" %Add0)
print("\t- Complete sentence 0 = {}".format(New0))
 
print("\nUsing a function")
def Complete(Part):
    Add = 'beautifull'
    ldict = locals()
    exec("New = Part + '%s'" %Add,globals(),ldict)
    New = ldict['New']
    print("\t- Complete sentence 1 = {}".format(New))
    print("\t- Complete sentence 2 = %s" %(New))
     
Complete(Sentence)

Output:without using a function
        - Complete sentence 0 = World is beautifull

Using a function
        - Complete sentence 1 = World is beautifull
        - Complete sentence 2 = World is beautifull

RE: exec in a function - paul18fr - Apr-19-2021

Thanks Yoriz for pointing out the issue.

Another solution seems to use globals() function as a dictionnary (key + value)

Sentence = "World is "
 
print("without using a function")
Add0 = 'beautifull'
exec("New0 = Sentence + '%s'" %Add0)
print("\t- Complete sentence 0 = {}".format(New0))
 
print("\nUsing a function")
def Complete(Part):
    Add = 'beautifull'
    globals()["New"] = Part + Add
    print("\t- Complete sentence 1 = {}".format(New))
    print("\t- Complete sentence 2 = %s" %(New))
     
Complete(Sentence)

Output:without using a function
	- Complete sentence 0 = World is beautifull

Using a function
	- Complete sentence 1 = World is beautifull
	- Complete sentence 2 = World is beautifull

RE: exec in a function - ndc85430 - Apr-19-2021

Why do you want to use exec in the first place? Writing code in strings that you glue together just makes it harder to understand the program. Sure, there are likely cases where you do need exec, but I think those are quite rare.

RE: exec in a function - paul18fr - Apr-19-2021

(Apr-19-2021, 07:59 AM)ndc85430 Wrote: Why do you want to use exec in the first place?

It's a basic code especially created to highlight the issue I was confronted to Wink