Tcl commands are evaluated if the command name is the first word, at the beginning of a line or when bracketed. [eval] evaluates its arguments in some special ways (concateneates to a string, if not a [pure list]). Here are some apocryph alternatives:

Andreas Leitgeb pointed out on the comp.lang.tcl newsgroup (2002-08-07) that

 if 1 $cmdis clearly faster then

 eval $cmdSee [Many ways to eval] for the ensuing discussion.

MS explained: "Well: eval does not bytecompile the script as it is "usually" used for one-time scripts ... For more fast-and-surprising ways to do it, try one of

     interp eval {} $x
     namespace eval :: $x

as they both will compile the script."
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[Tcl chatroom], 2002-12-18:

suchenwi	Another wrinkle is that [eval] does not byte-compile - for that you may use [[if 1]], [[interp eval {}]] or [[namespace eval ::]] ... 

EE	HOW many different eval commands are there?

dgp	YM: [[namespace eval [[namespace current]]]]

suchenwi	But such things are not documented features and may change between releases, so don't bet on it. - How many? The four above, and there's also [[uplevel 0]] ...
Don: yes - just quoting MS's hint, assuming that :: is current.

EE	eek.

suchenwi	Another way:
 foreach don't care {#body executed once, but may be left with break}
..which you could sugar as:
 interp alias {} breakable {} foreach _ _ ...

EE	ok, there should be a wiki page about how many different ways there are to eval a command. (With discussions of relative merit, of course, and obfuscatory value if you like it that way...)

suchenwi	BTW: change the above to: foreach don't {} {#and the body is not executed, like if 0 }

EE	yes, I like that. [[breakable]] looks good.

suchenwi	Well I'm not sure whether these really deserve propaganda - it's rather against [KISS] and all that...

EE	really? that doesn't execute the body with don't set to {} ?

miguel	foreach eval wayto {gimme $1}