Numeric Line Labels

[CJason]

Is it true that you can't have a line label that starts with a number??? If so, why would that be a restriction!???!

 

[KevinADC]

What is a line label?

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- Kevin, perl coder unexceptional!

 

[stevexff]

No, I never use them either. It's when you name a line with the name: construct for loop control and for those who like that sort of thing, goto. In the Perl doc labels are always shown as upper case, but I don't know if that's actually a restriction.

I guess Perl has rules about the kind of stuff it has in its symbol table and namespaces, and they can't start with numerics. It's quite a common restriction in many languages. If it's a problem for your code converter, can't you just stick a hard coded literal ('X' springs to mind) on the front?

Steve

[small]"Every program can be reduced by one instruction, and every program has at least one bug. Therefore, any program can be reduced to one instruction which doesn't work." (Object:erlDesignPatterns)[/small]

 

[KevinADC]

ahh, those labels. Its ture you can't use a number, probably because in perl numbers don't have to be quoted:

$foo = 1;

So I suspect a construct like this would be seen as a syntax error.

1:

Labels are a must if you have embedded loops, the perl style guide encourages perl coders to use them.




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- Kevin, perl coder unexceptional!

 

[rvBasic]

The Programming Perl bible by Larry Wall et. al. learns us (p 114)

If present, the label consists of an identifier followed by a colon. It's customary to make the label uppercase to avoid potential confusion with reserved words, and so it stands out better. And although Perl won't get confused if you use a label that already has a meaning like if or open, your readers might

combined with (p49)

An identifier is a token that starts with a letter or underscore and contains only letters, digits and underscores

we may conclude that digits are not allowed as the first character of an identifier, including labels.

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In theory, there is no difference between theory and practice. In practice, there is. [attributed to Yogi Berra]

 

[CJason]

Thanks guys. I kind of combined all these posts and tacked on an "_" before the line labels that are causing the problems.

Thanks again!