Revision as of 13:29, 13 September 2018

mIRC Script Language is an interpreted language - which means that mIRC has to work out what each statement means each and every time it is executed. Consequently it is not considered a fast language and, more often than not, the easiest implementation is not the fastest.

That said, PCs today are far more powerful then when mIRC first introduced its scripting language, and unless your script is processing large number of messages or large files, then performance is less of an issue than it used to be. On the other hand, the maintainability of your script is also important, so eliminating duplicate code using common aliases & identifiers is also beneficial even if it introduces some minor overheads.

The following tips will help to increase the execution speed of a script. Most will have a very marginal speed advantage and may not be worth consideration outside of long-running script blocks such as loops.

Use built-in functionality

Because mIRC interprets each statement every time it executes it, reducing the number of statements executed is the easiest way to improve the performance of your scripts. By contrast, once mIRC has worked out what the statement is, then the execution is done by mIRCs compiled code. You can often replace several statements or even entire loops by clever use of mIRCs broad range of built-in functionality. Here are some examples of common ways to reduce the number of statements:

Use Token Manipulation to break strings into pieces

If you want to get the first part of a string up to (say) the first full-stop, don't use $pos to find the position of this character, and then use $left or $right to get the relevant sub-string. Instead use mIRCs Token Manipulation functionality: $gettok(%string,1,$asc(.)) to get the first sentence and $gettok(%string,2-,$asc(.)) to get the remainder of the paragraph.

Benchmark:

/benchmark -ai100000 $gettok(Sentence. Sentence.,1,$asc(.));$left(Sentence. Sentence.,$pos(Sentence. Sentence.,.))

Use Wildcard-Matching

Wildcard-matching allows you to see if your string matches a wildcard template containing fixed text and wildcard-match characters ?, * and &.

"?" match any character
"*" match 0 or more characters
" & " match any word

So if you want to see if a string contains the word "fat" then you can use:

if (* fat * isin %string) echo -a I am not fat!!

Wildcard-matches can be used in /if statements, but also in token manipulation, hash tables, custom windows, ON events, variables, etc. etc. Even if you cannot narrow it down to a single item, using wildcard-matches to reduce substantially the number of iterations of a loop is very beneficial.

So for example, if we want to find a particular line in a custom window, rather than:

var %i $line(@custwin,0)
while (%i) {
  var %l = $line(@custwin,%i)
  if (The cat sat on the * iswm %l) echo -a I have found what the cat sat on. %l
  dec %i
}

the following code loops far fewer times and is therefore much quicker:

var %match The cat sat on the *, %i $fline(@custwin,%match,0)
while (%i) {
  var %l = $fline(@custwin,%match,%i)
  echo -a I have found what the cat sat on. %l
  dec %i
}

Use regular expressions

Regular expressions are a very powerful text search and replacement tool even if they have a significant learning curve.

Again, regular expressions can be used in hash tables, ON events, etc. etc.

Use hash tables

If you have a list of wildmatches you want to search for, store them in a hash table and use $hfind so that with one statement mIRC loops through the wildmatches to find one which is a match for your string.

Optimise to help mIRC be faster

Some mIRC Scripting Language constructs are faster than others...

Organization

Aliases at the top of script files have faster access speeds than if placed at the bottom of the script. Furthermore, aliases in scripts at the top of the script-order have faster access speeds than those at the end.

Alias Bypassing

When calling any form of command or identifier mIRC will attempt to find a scripted version prior to looking for a native equivalent. This functionality can be bypassed by prefixing commands with ! and by inserting a ~ after the $ of identifiers.

For example, this bypasses mIRC looking for a scripted echo alias:

/!echo -a Message

Benchmark:

/benchmark -aci100000 !set -l %a 2;set -l %a 1

Alternatively this bypasses mIRC looking for a scripted me alias¹:

echo -a $~me

¹: Even though mIRC will use its own native identifiers over custom aliases of the same name, there is still some pre-evaluation that can be bypassed using the above method.

Benchmark:

/benchmark -ai100000 $~left(abc,2);$left(abc,2)

Conditions

Best to worst:

if (condition) command
if condition { command }
if (condition) { command }

Benchmark:

/benchmark -aci100000 if (0 == 1) var %a 1;if 0 == 1 { var %a 1 };if (0 == 1) { var %a 1 }

/if vs. $iif()

$iif() is much slower than using an if-else statement. When $iif() is encounter it is first rearranged into an if-else statement and the result is evaluated.

Best to worst:

if (condition) var %result = condition_true_value
else var %result = condition_false_value

var %result = condition_false_value
if (condition) var %result = condition_true_value

var %result = $iif(condition, condition_true_value, condition_false_value)

Benchmark:

/benchmark -aci100000 if (condition) var %result = condition_true_value | else var %result = condition_false_value;var %result = condition_false_value | if (condition) var %result = condition_true_value;var %result = $iif(condition, condition_true_value, condition_false_value)

/tokenize & $n vs $gettok()

For successive² calls against the same data, it is faster to use /tokenize and $n over $gettok().

;; faster than using $gettok(a b c, 1, 32) $gettok(a b c, 2, 32)
tokenize 32 a b c
echo -a $1 $2

²: even with just two references against the same input tokenizing is faster than using $gettok

[ ]s vs $() vs $eval

Best to worst:

[ eval_statement ]
$(eval_statement, 2)
$eval(eval_statement, 2)

Benchmark:

//set %test.eval = VALUE
//echo -a [] %test. [ $+ eval ]
//echo -a $ $($+(%,test.,eval),2)
//echo -a $ $+ eval $eval($+(%,test.,eval),2)
/benchmark -ai100000 %test. [ $+ eval];$($+(%,test.,eval),2);$eval($+(%,test.,eval),2)

/var vs /set

multiple /set -l to set local variables is much faster than /var because /var has to parse the line and call /set for each variable anyway.