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| author | M.J.T. Guy <mjtg@cus.cam.ac.uk> | 1997-06-15 19:27:52 +1200 |
|---|---|---|
| committer | Tim Bunce <Tim.Bunce@ig.co.uk> | 1997-08-07 00:00:00 +1200 |
| commit | 5e77893f7750cb306f72f716d77774596666441f (patch) | |
| tree | 9d54abc3c0adf5f7b42ee25c368fd539fe4562b9 /pod/perltrap.pod | |
| parent | 8dbef6988b4d46823e28b4caabe5a76ed664f7aa (diff) | |
| download | perl-5e77893f7750cb306f72f716d77774596666441f.tar.gz | |
perl4 to perl5.004 converion with debugger problem
jmm@elegant.com (John Macdonald) wrote
> The other issue is an annoyance rather than a stopper. As cited
> in perl425traps, "stuff${'var}more stuff" is no longer
> supported, only $::var and ${::var} are recognized with a
> string. Changing the ' to :: means that the code is no longer
> perl4 compatible. I don't want to have ongoing work on two
> versions (perl4 and perl5), so the only good workaround, for
> now, is to break the string into:
>
> "stuff" . $'var . "more stuff"
>
> As I said, it's an annoyance - there's lots of them in the code
> and a significant proportion of the conversions to . would cause
> lines that ought to be wrapped for readability purposes.
>
> Is there any hope of getting the $' syntax recognized within
> strings? (Sigh, I'm sure it's too late for it to go into
> 5.004_01, though.)
I think it would be a very bad idea to retrofit this. Having single
quotes which don't start quoted strings is a syntactic ambiguity
nightmare. Consider soft references such as "stuff${'var'}more stuff".
(I presume that's why it had to be removed.)
You can avoid this problem, and not extend the lines quite as much, by
explicitly including the package name:
"stuff${main'var}more stuff"
which works compatibly in perl4 and perl5.
Attached is a suggested patch for perltrap.
p5p-msgid: E0wdKJY-00010w-00@taurus.cus.cam.ac.uk
Diffstat (limited to 'pod/perltrap.pod')
| -rw-r--r-- | pod/perltrap.pod | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/pod/perltrap.pod b/pod/perltrap.pod index 7ba57d0c70..9382789969 100644 --- a/pod/perltrap.pod +++ b/pod/perltrap.pod @@ -438,6 +438,12 @@ whether this should be classed as a bug or not. # perl4 prints: x=10 # perl5 prints: Can't find string terminator "'" anywhere before EOF +You can avoid this problem, and remain compatible with perl4, if you +always explicitly include the package name: + + $x = 10 ; + print "x=${main'x}\n" ; + Also see precedence traps, for parsing C<$:>. =item * BugFix |