Length limit for variable names in your language?

Length limit for variable names in your language?

[No Na Me]

What this limit is for
C++,Fortran,Lisp,Pascal etcetcetc ?

Since this is multi-newsggroups message
please do not forget to mention the language :-)
Thanks

Re: Length limit for variable names in your language?

[Larry Kilgallen]

In article <3AFE60D8.6C3282B7@my-deja.com>, No Na Me <No_Na_Me@my-deja.com> writes:
> What this limit is for
> C++,Fortran,Lisp,Pascal etcetcetc ?

Section 2.2 of the Ada95 Language Reference Manual says that any
conforming compiler must support lexical elements of at least 200
characters in length.

Individual compilers are free to support more, but that caused me
pain when I tried to move a (mechanically generated) program from
a compiler that supported more than 200 character identifiers (an
Ada83 compiler, actually) to a compiler that set the limit at 200.
My mechanical program generation had some identifiers longer than
200 characters (to preserve information from which the program was
generated).

==============================================================================
Great Inventors of our time: Al Gore -> Internet; Sun Microsystems -> Clusters
==============================================================================

Re: Length limit for variable names in your language?

[Mark Yudkin]

IBM OS PL/I: 31
IBM VA PL/I: 100

"Larry Kilgallen" <Kilgallen@eisner.decus.org.nospam> wrote in message
news:WQs7DB0rYxJ6@eisner.encompasserve.org...
> In article <3AFE60D8.6C3282B7@my-deja.com>, No Na Me
<No_Na_Me@my-deja.com> writes:
> > What this limit is for
> > C++,Fortran,Lisp,Pascal etcetcetc ?
>
> Section 2.2 of the Ada95 Language Reference Manual says that any
> conforming compiler must support lexical elements of at least 200
> characters in length.
>
> Individual compilers are free to support more, but that caused me
> pain when I tried to move a (mechanically generated) program from
> a compiler that supported more than 200 character identifiers (an
> Ada83 compiler, actually) to a compiler that set the limit at 200.
> My mechanical program generation had some identifiers longer than
> 200 characters (to preserve information from which the program was
> generated).
>
>
============================================================================
==
> Great Inventors of our time: Al Gore -> Internet; Sun Microsystems ->
Clusters
>
============================================================================
==

Re: Length limit for variable names in your language?

[Edward Rosten]

> What this limit is for C++,Fortran,Lisp,Pascal etcetcetc ?

According to K&R 2nd edition, C guarntees that at least the first 31
characters of an internal name are significant. The standard guarntees 6
monocase characters for external identifiers, minimum.

-Ed


 
> Since this is multi-newsggroups message please do not forget to mention
> the language :-) Thanks



-- 
You can't go wrong with psycho-rats.

u 9 8 e j r (at) e c s . o x . a c . u k

Re: Length limit for variable names in your language?

[Cesar Rabak]

Edward Rosten wrote:
> 
> > What this limit is for C++,Fortran,Lisp,Pascal etcetcetc ?
> 
> According to K&R 2nd edition, C guarntees that at least the first 31
> characters of an internal name are significant. The standard guarntees 6
> monocase characters for external identifiers, minimum.
> 
> -Ed

The present standard (a.k.a. C99) changes this to:

         -- 63  significant  initial  characters  in  an   internal
            identifier  or  a  macro name (each universal character
            name or  extended  source  character  is  considered  a
            single character)

         -- 31   significant  initial  characters  in  an  external
            identifier (each universal character name specifying  a
            character  short  identifier  of  0000FFFF  or  less is
            considered 6 characters, each universal character  name
            specifying  a character short identifier of 00010000 or
            more is considered 10  characters,  and  each  extended
            source  character  is  considered  the  same  number of
            characters as  the  corresponding  universal  character
            name, if any)

Since presently no C compiler is 100% compliant to the standard, YMMV.

HTH

Cesar

Re: Length limit for variable names in your language?

[Edward Rosten]

In article <3AFF40AF.C7FB3D9C@uol.com.br>, "Cesar Rabak"
<csrabak@uol.com.br> wrote:

> Edward Rosten wrote:
>> 
>> > What this limit is for C++,Fortran,Lisp,Pascal etcetcetc ?
>> 
>> According to K&R 2nd edition, C guarntees that at least the first 31
>> characters of an internal name are significant. The standard guarntees
>> 6 monocase characters for external identifiers, minimum.
>> 
>> -Ed
> 
> The present standard (a.k.a. C99) changes this to:

I was referring to the C89(?) standard. C89 compliant (or nearly)
compilers are still much more common. However things depending on
external linkage are really at the mercy of the linker and library
software opn the host system.

-ed



-- 
You can't go wrong with psycho-rats.

u 9 8 e j r (at) e c s . o x . a c . u k

Re: Length limit for variable names in your language?

[Larry Kilgallen]

In article <9do3c2$2e$1@news.ox.ac.uk>, "Edward Rosten" <look@my.sig> writes:
> In article <3AFF40AF.C7FB3D9C@uol.com.br>, "Cesar Rabak"
> <csrabak@uol.com.br> wrote:
> 
>> Edward Rosten wrote:
>>> 
>>> > What this limit is for C++,Fortran,Lisp,Pascal etcetcetc ?
>>> 
>>> According to K&R 2nd edition, C guarntees that at least the first 31
>>> characters of an internal name are significant. The standard guarntees
>>> 6 monocase characters for external identifiers, minimum.
>>> 
>>> -Ed
>> 
>> The present standard (a.k.a. C99) changes this to:
> 
> I was referring to the C89(?) standard. C89 compliant (or nearly)
> compilers are still much more common. However things depending on
> external linkage are really at the mercy of the linker and library
> software opn the host system.

In order to meet the Ada length requirements, the Compaq Ada compiler
uses another mechanism that the linker for connections between Ada
modules, using the normal linker mechanism to implement that other
mechanism.  Thus there is no degradation of name length between Ada
modules.

I presume other Ada compilers do something similar, but I am less
familiar with the linking mechanisms in those cases.  Supporting
the full length of identifiers with all characters significant is
a guarantee that is important to Ada programmers, as is portability
between various implementations.

Re: Length limit for variable names in your language?

[Rev. Bob 'Bob' Crispen]

If y'all promise to take comp.lang.vrml off the followups (fascinating 
though the topic is), I'll give you the skinny on VRML symbolic names:

VRML browsers are required to support up to 50 utf8 octets for symbolic 
names for PROTOs, DEFs, and fields (the only place they apply).  Ref: 
ISO/IEC-14772-1:1997, Clause 7.3.3.

Although VRML files can inline other VRML files, each file has its own 
namespace, so linker considerations don't apply, since the language is 
neither compiled nor linked.

ECMAScript scripts inside VRML files follow ECMA-262, which requires 
symbolic names to be of "unlimited" length.  Ref: ECMA-262, Clause 7.5.
-- 
Rev. Bob "Bob" Crispen
crispen at hiwaay dot net

Am I getting smart with you? ....How would you know?

Re: Length limit for variable names in your language?

[Tim Tyler]

Java - from the end of:

  http://java.sun.com/docs/books/vmspec/html/ClassFile.doc.html

``The amount of code per method is limited to 65535 bytes by the sizes of
  the indices in the exception_table of the Code attribute (�4.7.4), in
  the LineNumberTable attribute (�4.7.6), and in the LocalVariableTable
  attribute (�4.7.7).''

I believe this is the major limitation that might reflect on
the maximum length of local variable names in Java bytecode.

I can't find any maximum limit on the length of static variables - this
might in principle depend on the availablility of memory.

Since these limits are in the VM specification - and no limits appear to
be specified in the language specification - a compiler may be at liberty
to rename private variables to avoid the issue.
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