Frink 2.2

The latest version of Frink is always available by ftp from catless.ncl.ac.uk in the /pub directory: ftp://catless.ncl.ac.uk/pub/frink.tar.gz

Frink is a tcl formatting and static check program. It can prettify your program, minimise, obfuscate or just sanity check it. It can also do some rewriting.

If you want to just check the program without formatting use the -J flag. This causes all the heuristics to be applied but no tcl output generated. If you add the -U flag then you get some extra hardline checking. Please note that at the moment some of the heuristics will only work correctly when the -J flag is used.

You pass it filenames (or the stdin) and the output is generated to stdout. There are a variety of options you can pass in :

-a
add spaces after {} and "" when processing -command. (default = OFF)
-A
turn OFF special processing of expr commands.
-b
add braces (see manual page for details) (default = OFF)
-B
turn OFF processing code passed to the bind command.
-c <n>
set further indent for continuations to n. default = 2
-d
remove braces in certain (safe) circumstances (default = OFF)
-e
produce "else". default = OFF
-E
extract constant strings. (not implemented yet)
-f
rewrite some strings to use msgcat
-F<n>
selectively control which heuristics are used. Currently the parameter is a single hex coded number with each bit representing a test. If you prefix the bitstring with ! then the negation of the value is used. The values you need to know are:
00001 append parameter testing
00002 lappend parameter testing
00004 set parameter testing
00008 regexp parameter testing
00010 return checks
00020 check for : or ::: in names
00040 expr checks
00080 foreach var checking.
00100 check missing parameters
00200 check -switches on commands (*not* tk options!!)
00400 check for abbreviations of options
00800 check for unused variables
01000 check for bad name choice
02000 check for array usage
04000 check for possible name errors
-g
indent switch cases. default = OFF
-h
print information about options.
-H
turn on heuristic tests and warnings. (default = OFF)
-i <n>
set indent for each level to n. default = 4
-I
Treat elseif and else the same way. (default = OFF)
-j
remove non-essential blank lines. (default = OFF)
-J
Just do checks, no output. (default = OFF)
-k
remove non-essential braces. (default = OFF)
-K <f>
Specify file of extra code specs (see below for details).
-l
try for one-liners
-m
minimise the code by removing redundant spacing. default = OFF
-M
Warn about switch statements with no --. (default = OFF)
-n
do not generate tab characters. default = OFF
-N
do not put a newline out before elseif. default = OFF
-o
obfuscate : default = OFF
-O <t>
Don't format lines starting with token "t"
-p <v>
If v is a number produce that many blank lines after each proc definition, otherwise produce whatever format the code indicates. No codes are defined yet..... (default = do nothing)
-P
Turn off processing of "time" command (default = OFF)
-q
Add spaces round the conditions in if and while statements. (default = OFF)
-Q
warn about unquoted constants - not fully operational (default = OFF)
-r
remove comments. default = OFF
-s <c>
format according to style name "c". (no style names defined yet)
-S
Stop preserving end of line comments. default = OFF
-t <n>
set tabs every n characters.
-T
produce "then". default = OFF
-u
Safe to remove brackets from round elseif conditions. default = OFF
-U
Hardline checking enabled. Will be strict about presence of --. Complains about switches with no default. Complains about 1 used without brackets in while/for condition. default = OFF
-v
put { } round variable names where appropriate.
-V
The current version number
-w <n>
set line length. default = 80
-W
halt on warning.
-x
produce "xf style" continuations
-X
recognise tclX features
-y
Don't process -command (default = OFF)
-Y
Try to process dynamic code (default = OFF)
-z
Put a single space before the \ character on continuations.
-Z
Control heuristics that are tested. (-H turns on ALL tests

Please try it and let me know how else you would like to be able to tailor the output. (And all the bugs you find as well) Currently it is geared very much towards the style of tcl programming that I use myself.

Obfuscation is not particularly sophisticated yet. In particular it can be (in most cases) reversed by running the obfuscated program through frink again!

Frink uses quite a few heuristics (i.e. a bunch of ad hoc hacks) to improve both formatting and minimisation. In some obscure cases these may burn you. Please let me know of any cases you find. Suggestions for new heuristics are always welcome.

Currently frink supports straightforward tcl (it doesn't do case either), tclX and [incr tcl] 1.0. N.B. frink assumes that you are running it over a correct tcl program. If this is not the case then all bets are off! There are some constructions possible in tcl where it is impossible to determine the correct formatting except at runtime. If you use these, sorry, but frink can't help you.

Comment handling is not brilliant - suggestions are welcome for how it could be improved.....

Embedded Control

You can control frink's actions using embedded comments, thusly:

      # FRINK: nocheck
      set $b ffff

will cause the warning that the heuristic tests would generate to be silenced for the next line. You can substitute the word PRAGMA for FRINK if you so wish. (Currently they need to be in upper case - I may allow lower case as well in the future). The options available are currently:

nocheck
don't do any heuristic checks on the next line
noformat
don't try to do any clever formatting of the next line
notreached
this section of the code is never reached. This is probably redundant now that frink detects unreachable code itself. It will probably vanish in a future release.
returnok
used before a return not nested in a proc will suppress the usage warning.

set
This must be followed by a sequence of variable names. These will all be marked as being set. This stops reports of 'used before set'.
unused
This must be followed by a sequence of variable names. This will stop the variables being reported as unused.
array
This must be followed by a sequence of variable names. This will mark the names as referring to arrays.

restrictions (which will probably be lifted soon):

Rewriting

Frink will try to detect the cases where you use the options -text or -label and can rewrite the string passed in to use the message catalogue. Thus

label .foo -text "This is an example"

would become

label .foo -text [::msgcat::mc "This is an example"]

If Frink detects the the string is already of the form

[::msgcat::mc ......]

then it does not rewrite. N.B. Frink does not generate the package require msgcat statement for you!!!!

Heuristics

Frink applies a variety of heuristics to the tcl code to try to detect possible errors. Note that sometimes the things that it points out are not in fact incorrect. At the moment the checks it does are as follows:

  1. detects if certain commands are used without parameters.
  2. checks that the correct values are passed through as options to built in commands (e.g. string, interp etc.) N.B. Frink does not let you abbreviate the options as tcl does - this is intentional as it is a poor programing practice for several reasons. (I might implement a flag that allows this in the future though)
  3. detects certain cases where too many or too few parameters are provided.
  4. detects "\ " at the end of a line (bad continuation usually).
  5. detects missing }, ] and ".
  6. detects when non-constant strings are passed as the first parameter to set, append and lappend. Also checks other statements where variable names are expected (global, unset etc.)
  7. detects variable names with single or more than two sequential colons in them.
  8. detects exprs where the expression is not braced.
  9. detects some missing ) cases.
  10. detects break not used in a bind or in a loop, and return used outside a proc
  11. detects where return is used inconsistently (i.e. sometimes you return a result, sometimes not). Picks up missing returns at end of procs that return results too.
  12. checks nested foreach statements to see if variables get reused.
  13. checks for possible -switch problems

I have other heuristic tests planned, and if you have any suggestions for tests I can implement please let me know.

Extending the analysis

The -K flag allows you to specify a file that describes new commands to Frink so that it can format/check them correctly. The syntax is very simple.

  1. comment lines start with a #
  2. blank lines are ignored
  3. definition lines start with the name of the command and are followed by a specification of the parameters. These tell Frink what to expect in these positions and what formatting/checks it should therefore carry out.

Here are some specs for commands that you already are familiar with:

append {var any args}
append's first parameter is a variable name
the second can be anything and this can be followed by 0 or more parameters.

I am changing some of the internals here so the available features change. When they settle down I'll document them fully....