OpenEuphoria

Re: Win32lib and handles

• Posted by Derek Parnell <ddparnell at bigpond.com> Dec 04, 2002
• 559 views

On Tue, 3 Dec 2002 16:13:15 -0600, Kat <kat at kogeijin.com> wrote:

> On 4 Dec 2002, at 7:47, Derek Parnell wrote:
>
>>
>> Thanks for the additional trace info. However this only further confuses 
>> me.
>> There are a number of Very Weird Things in this trace.
>>
>> > C:\EUPHORIA\include\win32lib.ew:1089 in function w32Func()
>> > type_check failure, grabbedHDC is 11824360
>>
>> In the library file there are three places that assign grabbedHDC (a
>> sequence BTW). They are ...
>>
>> grabbedHDC = prepend( grabbedHDC, {pID, lhDC, lSavedDC, lOrigResource} )
>>
>> grabbedHDC = removeIndex(lPos, grabbedHDC)
>>
>> grabbedHDC = prepend( grabbedHDC, {id,hdc, 0, {}} )
>>
>> The two using 'prepend' obviously result in a sequence, so no type-check
>> error there. The one using removeIndex resolves to this statement ...
>>
>> return list[1 .. index-1] & list[index+1 .. length(list)]
>>
>> which because of the concatenation operation also results in a sequence. 
>> Yet the
>> trace seems to crash 'cos an atom is  being assigned to it. Very Weird!
>
> I found a case where strtok is complaining of the results of a parse. If 
> a subseq is one character, it seems to be getting retyped to an atom, 
> which crashes the next function to use it. All i can do is test lengths 
> and use a {} if it's a single character, i spose. If i get time to do 
> anything about it...

Kat,
are you suggesting that the problem might lie inside Euphoria? That under 
some conditions that either a concatenation returns an atom or something 
like that?

> Oh, and i have been having troubles using &= to append things, more than once 
> i have had nests built where none was intended, and vice versa.

For the benefit of Eu new comers, here's how I remember when and how to use 
&=

'&' appends every element and 'append' only every appends one element. In 
other words...
'&' treats the new object a list of elements to be appended, and 'append' 
treats the new object as a single element.

a ={1}
a  &= "abc"  -- this adds 3 elements, namely 'a', 'b' and 'c'
==> {1,'a', 'b','c'}  -- length of a is increased by 3 a= {1}
a = append(a, "abc") -- this adds one element, namely {'a','b','c'}
==> {1,{'a','b','c'}} -- length of a is increased by 1.

Thus a = append(a,x) is equivelent to a &= {x}


Robert Craig:
Can you confirm that Euphoria will always return a sequence for a 
concatenation operation?

-- 

cheers,
Derek Parnell