Hi Tassilo,
In article <[EMAIL PROTECTED]>, Tassilo Von Parseval wrote:
> On Sun, Jun 01, 2003 at 11:22:32AM +0200 Kevin Pfeiffer wrote:
>
>> More problems trying to use constants...
>>
>> I have:
>>
>> use constant CFG => qq|$ENV{'HOME'}/.get_quiz|;
>>
>>
>> But I can't see how to make this work:
>>
>> open DATA, "> CFG" or die "Couldn't open ", CFG, " for writing: $!\n";
>>
>> With quote marks it creates a new file in the pwd called "CFG". (Maybe
>> it's time to get the Programming Perl book?)
>
> A constant neither has the $ nor @ sigil in front so it wont
> interpolate in strings. Oddly enough you did the right thing in the 'or
> die' string. The second argument to open() is not different: It's just a
> string.
>
> To get around that, you can use the three-argument form of open():
>
> open DATA, ">", CFG or die ...;
I was so close! (I quoted the '>' but I left out the comma following.)
> if your Perl is recent enough (>= 5.6.0). Or you use the
> interpolate-anything trick:
>
> open DATA, ">@{[ CFG ]}" or die ...;
>
> The part between @{[ ]} is arbitry Perl-code that is executed in list
> context and the last expression evaluated in this Perl code is what gets
> eventually printed.
This seems too confusing here for me (but I will add it to my save file for
future reference.)
> Btw: You probably shouldn't use the DATA handle. It's special in that it
> refers to anything that follows the __DATA__ or __END__ token in your
> scripts. It even is seekable so you can write a script that prints
> itself with the help of this filehandle.
I almost asked about this earlier - if a script can also write to itself. I
wrote something to test it, but haven't had time to look up the seek
functions, etc. I suppose this only makes sense in very limited situations
(if at all)?
Thanks!
-K
--
Kevin Pfeiffer
International University Bremen
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