Maximum Method Name Length

问题:

Does anyone happen to know what the maximum length of a method name is in your programming language of choice? I was going to make this a C# specific question, but I think it would be nice to know across the spectrum.

What are the factors involved as well:

• Does the language specification limit this?
• What does the compiler limit it to?
  • Is it different on 32bit vs 64bit machines?

回答1:

For C# I don't believe there's a specified hard limit. (Section 2.4.2 of the C# 5 spec doesn't give a limit, for example.) Roslyn v2.2.0.61624 seems to have a limit of 1024 characters; this is way beyond the bounds of readability and even a sensible machine-generated name.

For Java, section 3.8 of the spec states:

An identifier is an unlimited-length sequence of Java letters and Java digits, the first of which must be a Java letter.

回答2:

PHP seems to be limited only by the script's memory limit.

With 128Mb I was able to create a class (and method) with 4 million characters.

<?php
ini_set('memory_limit', '128M');
$i = 1024 * 1024;

while ($i < 10000000)
{
    $className = str_repeat('i', $i);
    eval("class $className { public function $className() { echo '$i<br>'; } }");
    new $className();
    $i *= 2;
}

?>

回答3:

I just did a test in C# Visual Studio 2010 (x64): made an identifier:

int a123456789a123...;

And repeated. At 512 characters, VS gives me the error "Identifier too long." 511 is fine though. (Checked character count in Word.)

Another example:

int whyintheworldwouldyoueverhaveanidenfifierthislongitsreallyjustquiteridiculousimeancmonyoucouldatleasthavethecommoncourtesyofmakingitcamelcasesoitsnotsohardtoreadcmonjuststopnowyourereallyreachingtomakethisaslongaspossiblearentyou123412341234alrightwellthatsenoughnowisntitwelliguessnotbecauseimstillgoingthisisofficallytheworstidentifiereverಠ_ಠokaynowthatithasunicodeitsofficialbutseriouslythisthingissolongthatihadtogetupinthemiddleofittotakeabreakbeforesittingdowntofinishtoppingitofftothemaxcharlimitof___511;

回答4:

Microsoft's C# implementation is 511, VB.NET implementation is 1023.

Visual Studio will only colorize the first 511 (1023 for VB) characters of the identifier and keep the rest black.

回答5:

in C# is 511 characters length.

回答6:

Common Lisp symbols's names are strings; strings have a length limit of array-dimension-limit

The value of array-dimension-limit is a positive integer that is the upper exclusive bound on each individual dimension of an array. This bound depends on the implementation but will not be smaller than 1024. (Implementors are encouraged to make this limit as large as practicable without sacrificing performance.)

In practice this can be quite large

Welcome to Clozure Common Lisp Version 1.3-dev-r11583M-trunk  (DarwinX8664)!
? array-dimension-limit
72057594037927936
? 

Welcome to Clozure Common Lisp Version 1.3-dev-r11583M-trunk  (DarwinX8632)!
? array-dimension-limit
16777216
? 

This answer ignores the method name's package name; this could double the lengh.

回答7:

in Progress (OpenEdge) the limit is 32 char.

回答8:

In D I don't know this to be the case but I suspect that it is something insane like >100MB. It might be an out-of-memory thing. This is based on knowing that I and other people have run into object file format limitation of about 11kB for symbol names and that this has been fixed.

回答9:

In Java, I believe a length limit is not given. See this from the online Sun Java Tutorial:

Variable names are case-sensitive. A variable's name can be any legal identifier — an unlimited-length sequence of Unicode letters and digits, beginning with a letter...

Like others above, I would guess the length is dependent upon the available memory.

回答10:

Interesting! In Java as others said there is no limit (I never thought about the length!) but I think you want to avoid having a long method name as this could effect readability and even mental mapping (any other dev looking at the code may forget or want to forget the method name!).

I believe "clean code" in a nutshell talks about the use of descriptive pronounceable names. You could also argue a long descriptive name is better than a short one, I guess a sound balance. tis my humble view.