Reported bug to consider

[Antonio Linares]

A Harbour user has reported a bug, according to Clipper docs:

Enrico Maria Giordano reported bug

We do appreciate your opinions

many thanks

Antonio

[Bacco]

Does the aforementioned code works on Cl*pper as user expected?

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[Bacco]

That is always the first question, of course.

But it seems that the use of "return a reference" in the mentioned

docs lead to a wrong conclusion. I hope this snippets can clarify

what it means to return a reference;

Here we are returning a value:

a := {1,2,3}

? ATAIL(a)

And here, returning a "reference", as the value is in fact an array:

a := {1,2,{3,4,5}}
? ATAIL(a)[2]

ATAIL(a)[2] = 7 works...

It's expected in the first case you cant set a value to another value.

Regards

Bacco

[Alex Strickland]

Hi

I don't agree that that behaviour is a bug, I consider the fact that it works as Enrico expects in xHarbour to be a bug.

This quote:

It can be used in applications as shorthand for
<aArray>[LEN(<aArray>)] when you need to obtain the last element of an
array.

does not imply the behaviour he expects in my opinion.

Basically an expression cannot return a L-Value that can be assigned to unless it is a reference.

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Regards

Alex

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[Francesco Perillo]

Exactly.

ATAIL( a ) is a function, whatever it returns, you can't assign a value to it. Not in Clipper. Don't be mislead by some other languages.

More, please test it in xHarbour:

a := {1,2,3,4,5}
b := ATAIL(a)
? b
b := 8
? ATAIL(a)

In Harbour it always returns 5.

Looking at the c code, atail returns a copy of the last object in the array... so I can't even understand how can it work in xHarbour if the code is the same...

 

[José M. C. Quintas]

Yes, and no.

Atail() returns last array, ok.

array may be allways as reference, ok.

But if element is not an array, it is not by reference.

a := { { 1,2}, { 3,4} }

b := Atail(a) // returns an array

b[ 2 ] := 10 // change value

? Atail( a )[ 2 ] // show 10

this is not the same as

a:= { 1,2,3,4,5}

b := Atail(a) // returns a number

b := 10 // do not change a array

? Atail( a ) // show 5

Do you make the test using Clipper?

José M. C. Quintas

[Klas Engwall]

Hi Antonio,

> A Harbour user has reported a bug, according to Clipper docs:
>
> Enrico Maria Giordano reported bug

> <http://forums.fivetechsupport.com/viewtopic.php?f=18&t=41455&start=0&sid=0d8f9902f25fadfb880f19312b4aa537>

>
> We do appreciate your opinions

Clipper's opinion below :-)

L:\clip5\TEST>clipper enrico
Clipper (R) 5.2e
Copyright (c) 1985-1995, Computer Associates International, Inc.
Microsoft C Floating Point Support Routines
Copyright (c) Microsoft Corp 1984-1987. All Rights Reserved.
342K available
Compiling ENRICO.PRG
ENRICO.PRG(5) Error C2042 Invalid lvalue
1 error

Regards,
Klas

[Antonio Linares]

many thanks to all

best regards

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Antonio Linares
www.fivetechsoft.com

[José M. C. Quintas]

a := { 1, 2, 3 }

Test( a )

? a[ 3 ] // return 10

FUNCTION Test( a )

a[ 3 ] := 10

RETURN Nil

Works like Test( @a ), but not exactly the same.

This do not occurs with another value type, only with arrays.

José M. C. Quintas

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