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Undefined ProcedureReturn should be #False (0)
Posted: Tue May 22, 2018 9:04 pm
by es_91
The undefined return of a procedure is, practically, a random number.
It could be zero, i think it should.
However, if it is undefined, it could become 1 that would interfere with a situation where i test the function for success but the success was never set.
Code: Select all
Procedure function ()
ProcedureReturn
EndProcedure
If function ()
; should only be reached when return is set ProcedureReturn 1
; is reached nevertheless
Debug "hello"
EndIf
If function () = #True
; COULD equally be reached in few cases; should not be reacheable
Debug "HELLO AGAIN; WHAT A MISTAKE ;-)"
EndIf
But it should be zero.
Re: Undefined ProcedureReturn should be #False (0)
Posted: Tue May 22, 2018 9:13 pm
by wilbert
es_91 wrote:The undefined return of a procedure is, practically, a random number.
It could be zero, i think it should.
However, if it is undefined, it could become 1 that would interfere with a situation where i test
Code: Select all
if function () : ;only do when return is set with ProcedureReturn 1
endif
But it should be zero.
It is certainly not a random number.
ProcedureReturn without an argument returns the value of the cpu register eax / rax.
It’s very important it stays this way.
Re: Undefined ProcedureReturn should be #False (0)
Posted: Tue May 22, 2018 9:14 pm
by es_91
So, it surely never becomes 1/#True? OK. That's enough.
Re: Undefined ProcedureReturn should be #False (0)
Posted: Tue May 22, 2018 9:19 pm
by es_91
Oh, well, it does become 1. That is... i don't know...
Re: Undefined ProcedureReturn should be #False (0)
Posted: Wed May 23, 2018 2:53 am
by TI-994A
es_91 wrote:The undefined return of a procedure is, practically, a random number.
It could be zero, i think it should.
However, if it is undefined, it could become 1 that would interfere with a situation where i test the function for success but the success was never set...
This is a perfect scenario to illustrate the importance of good coding practices. While not always adhered to, and sometimes even debatable,
procedures should invariably contain only one single return.
Consider such a model:
Code: Select all
Procedure function ()
result = 0
If something
result = 1
ElseIf something_else
result = 2
EndIf
If result > 0
;further conditional processing
EndIf
ProcedureReturn result
EndProcedure
It's never a good idea to depend on compiler defaults; always assign required values explicitly.
Re: Undefined ProcedureReturn should be #False (0)
Posted: Wed May 23, 2018 4:49 am
by wilbert
es_91 wrote:Oh, well, it does become 1. That is... i don't know...
It depends on the assembly code PB generates.
If the value of eax/rax happens to be 1, ProcedureReturn will return a 1.
Why don't you simple write ProcedureReturn 0 instead of ProcedureReturn ?
Re: Undefined ProcedureReturn should be #False (0)
Posted: Wed May 23, 2018 8:32 am
by walbus
When writing functions which others should use, it is very important to always return a defined value
I myself always hold it that way:
1 OK
0 No error, but also no successful execution
-1, -2, -3 Error from a previously defined table
Re: Undefined ProcedureReturn should be #False (0)
Posted: Tue May 29, 2018 10:38 am
by uweb
Yes, but may it would be better to have on Standard for all - not only ProcedureReturn.
e.g.
Cool() instead of Bool() handles three cases (#True, #False and #NIL) instead of two.