tepam(n) Tcl's Enhanced Procedure and Argument Manager tepam(n)______________________________________________________________________________NAME
tepam - An introduction into TEPAM, Tcl's Enhanced Procedure and Argu‐
ment Manager
DESCRIPTION
This document is an informal introduction into TEPAM, the Tcl's
Enhanced Procedure and Argument Manager. Detailed information to the
TEPAM package is provided in the tepam::procedure and tepam::argu‐
ment_dialogbox reference manuals.
OVERVIEW
This package provides a new Tcl procedure declaration syntax that sim‐
plifies the implementation of procedure subcommands and the handling of
the different types of procedure arguments like flags or switches,
options, unnamed arguments, optional and mandatory options and argu‐
ments, default values, etc. Procedure declarations can be enriched with
detailed information about the procedure and its arguments. This infor‐
mation is used for the following purposes:
First of all, a preamble is added in front of the body of a procedure
that is declared with TEPAM. This preamble calls an argument manager
that that uses the provided information to check the validity of the
argument types and values before the procedure body is executed. Then,
the information is used to generate help and usage texts if requested,
or to generate clear error message in case an argument validation
fails. The information also allows generating automatically graphical
forms that allows an interactive definition of all arguments, in case a
procedure is called interactively. And finally, the additional informa‐
tion helps self-commenting in a clean way the declaration of a proce‐
dure and of all its arguments.
The graphical form generator that creates the necessary argument speci‐
fication forms for the interactive procedure calls is also available
for other purposes than for procedure argument specifications. It
allows creating code efficiently complex parameter entry forms that are
usable independently from TEPAM's new procedure definition method.
Here is a short overview about all major TEPAM features:
· New self-documenting procedure declaration syntax: The addi‐
tional information to declare properly a procedure has not to be
provided with additional statements, but can be added in a natu‐
ral syntax directly into the procedure header.
· Easy way to specify subcommands: A subcommand is declared like a
procedure, simply with a procedure name composed by a base name
followed by a subcommand name. Sub-subcommands are created iden‐
tically using simply procedure names composed by 3 words.
· Flexible usage of flags (switches), options (named arguments)
and unnamed arguments. Option names are optionally automatically
completed.
· Support for default values, mandatory/optional options and argu‐
ments, choice lists, value ranges, multiple usable options/argu‐
ments.
· Choice of a named arguments first, unnamed arguments later pro‐
cedure calling style (typical for Tcl commands) or of an unnamed
arguments first, named arguments later procedure calling style
(typical for Tk commands).
· In case the named arguments first, unnamed arguments later style
(Tcl) is selected: Clear separation between options and argu‐
ments via the "--" flag. The unnamed arguments can optionally be
accessed as options (named arguments).
· Automatic type and value check before the procedure body is exe‐
cuted, taking into account validation ranges, choice lists and
custom validation commands. Generation of clear error message if
necessary.
· Many predefined types exist (integer, boolean, double, color,
file, font, ...). Other application specific types can easily be
added.
· Automatic help and usage text generation if a procedure is
called with the -help flag.
· Automatic generation of an interactive argument definition form,
in case a procedure is called with the -interactive flag.
· Procedure calls can be logged which is useful to get for inter‐
actively called procedures the command call lines.
· Powerful and code efficient generation of complex parameter def‐
inition forms.
PROCEDURE DECLARATION
TEPAM's procedure declaration syntax is simple and self-explaining.
Instead of declaring a procedure with the Tcl key word proc, a proce‐
dure is declared with the TEPAM command procedure which takes as proc
also 3 arguments: The procedure name, the procedure header and the pro‐
cedure body.
The following example declares the subcommand message of the procedure
display. This command has several named and unnamed arguments:
tepam::procedure {display message} {
-return-
-short_description "Displays a simple message box"
-description "This procedure allows displaying a configurable message box.
-args {
{-mtype -default Warning -choices {Info Warning Error} -description "Message type"}
{-font -type font -default {Arial 10 italic} -description "Message text font"}
{-level -type integer -optional -range {1 10} -description "Message level"}
{-fg -type color -default black -description "Message color"}
{-bg -type color -optional -description "Background color"}
{-no_border -type none -description "Use a splash window style (no border)"}
{-log_file -type file -optional -description "Optional message log file"}
{text -type string -multiple -description "Multiple text lines to display"}
}
} {
puts "display message:"
foreach var {mtype font level fg bg no_border log_file text} {
if {[info exists $var]} {
puts " $var=[set $var]"
}
}
}
A call of procedure that has been declared in this way will first
invoke the TEPAM argument manager, before the procedure body is exe‐
cuted. The argument manager parses the provided arguments, validates
them, completes them eventually with some default values, and makes
them finally available to the procedure body as local variables. In
case an argument is missing or has a wrong type, the argument manager
generates an error message that explains the reason for the error.
As the example above shows, the TEPAM command procedure accepts subcom‐
mand definitions as procedure name and allows defining much more infor‐
mation than just the argument list inside the procedure header. The
procedure body on the other hand is identical between a command
declared with proc and a command declared with procedure.
The procedure header allows defining in addition to the arguments some
procedure attributes, like a description, information concerning the
return value, etc. This information is basically used for the automatic
generation of comprehensive help and usage texts.
A list of argument definition statements assigned to the -args argument
is defining the procedure arguments. Each argument definition statement
starts with the argument name, optionally followed by some argument
attributes.
Three types of arguments can be defined: Unnamed arguments, named argu‐
ments and flags. The distinction between the named and unnamed argu‐
ments is made by the first argument name character which is simply "-"
for named arguments. A flag is defined as named argument that has the
type none.
Named and unnamed arguments are mandatory, unless they are declared
with the -optional flag and unless they have a default value specified
with the -default option. Named arguments and the last unnamed argument
can have the attribute -multiple, which means that they can be defined
multiple times. The expected argument data type is specified with the
-type option. TEPAM defines a large set of standard data types which
can easily be completed with application specific data types.
The argument declaration order has only an importance for unnamed argu‐
ments that are by default parsed after the named arguments (Tcl style).
A variable allows changing this behavior in a way that unnamed argu‐
ments are parsed first, before the named arguments (Tk style).
PROCEDURE HELP
The declared procedure can simply be called with the -help option to
get the information about the usage of the procedure and its arguments:
display message -help
->
NAME
display message - Displays a simple message box
SYNOPSYS
display message
[-mtype <mtype>] :
Message type, default: "Warning", choices: {Info Warning Error}
[-font <font>] :
Message text font, type: font, default: Arial 10 italic
[-level <level>] :
Message level, type: integer, range: 1..10
[-fg <fg>] :
Message color, type: color, default: black
[-bg <bg>] :
Background color, type: color
[-no_border ] :
Use a splash window style (no border)
[-log_file <log_file>] :
Optional message log file, type: file
<text> :
Multiple text lines to display, type: string
DESCRIPTION
This procedure allows displaying a configurable message box.
PROCEDURE CALL
The specified procedure can be called in many ways. The following list‐
ing shows some valid procedure calls:
display message "The document hasn't yet been saved!"
-> display message:
mtype=Warning
font=Arial 10 italic
fg=black
no_border=0
text={The document hasn't yet been saved!}
display message -fg red -bg black "Please save first the document"
-> display message:
mtype=Warning
font=Arial 10 italic
fg=red
bg=black
no_border=0
text={Please save first the document}
display message -mtype Error -no_border "Why is here no border?"
-> display message:
mtype=Error
font=Arial 10 italic
fg=black
no_border=1
text={Why is here no border?}
display message -font {Courier 12} -level 10 \
"Is there enough space?" "Reduce otherwise the font size!"
-> display message:
mtype=Warning
font=Courier 12
level=10
fg=black
no_border=0
text={Is there enough space?} {Reduce otherwise the font size!}
The next lines show how wrong arguments are recognized. The text argu‐
ment that is mandatory is missing in the first procedure call:
display message -font {Courier 12}
-> display message: Required argument is missing: text
Only known arguments are accepted:
display message -category warning Hello
-> display message: Argument '-category' not known
Argument types are automatically checked and an error message is gener‐
ated in case the argument value has not the expected type:
display message -fg MyColor "Hello"
-> display message: Argument 'fg' requires type 'color'. \
Provided value: 'MyColor'
Selection choices have to be respected ...
display message -mtype Fatal Hello
-> display message: Argument (mtype) has to be one of the \
following elements: Info, Warning, Error
display message -level 12 Hello
-> display message: Argument (level) has to be between 1 and 10
INTERACTIVE PROCEDURE CALLS
The most intuitive way to call the procedure is using an form that
allows specifying all arguments interactively. This form will automati‐
cally be generated if the declared procedure is called with the -inter‐
active flag.
display message -interactive
The generated form contains for each argument a data entry widget that
is adapted to the argument type. Check buttons are used to specify
flags, radio boxes for tiny choice lists, disjoint list boxes for
larger choice lists and files, directories, fonts and colors can be
selected with dedicated browsers.
After acknowledging the specified argument data via an OK button, the
entered data are first validated, before the provided arguments are
transformed into local variables and the procedure body is executed. In
case the entered data are invalid, a message appears and the user can
correct them until they are valid.
The procedure calls can optionally be logged in a variable. This is for
example useful to get the command call lines of interactively called
procedures.
FLEXIBLE ARGUMENT DIALOG BOX
The form generator that creates in the previous example the argument
dialog box for the interactive procedure call is also available for
other purposes than for the definition of procedure arguments. TEPAM's
provided argument dialog box allows crating complex parameter defini‐
tion forms in a very efficient way.
The following example tries to illustrate the simplicity to create com‐
plex data entry forms. It creates an input mask that allows specifying
a file to copy, a destination folder as well as a checkbox that allows
specifying if an eventual existing file can be overwritten. Comfortable
browsers can be used to select files and directories. And finally, the
form offers also the possibility to accept and decline the selection.
Here is the code snippet that is doing all this:
tepam::argument_dialogbox \
-existingfile {-label "Source file" -variable SourceFile} \
-existingdirectory {-label "Destination folder" -variable DestDir} \
-checkbutton {-label "Overwrite existing file" -variable Overwrite}
The argument_dialogbox returns ok if the entered data are validated. It
will return cancel if the data entry has been canceled. After the vali‐
dation of the entered data, the argument_dialogbox defines all the
specified variables with the entered data inside the calling context.
An argument_dialogbox requires a pair of arguments for each variable
that it has to handle. The first argument defines the entry widget type
used to select the variable's value and the second one is a lists of
attributes related to the variable and the entry widget.
Many entry widget types are available: Beside the simple generic
entries, there are different kinds of list and combo boxes available,
browsers for existing and new files and directories, check and radio
boxes and buttons, as well as color and font pickers. If necessary,
additional entry widgets can be defined.
The attribute list contains pairs of attribute names and attribute
data. The primary attribute is -variable used to specify the variable
in the calling context into which the entered data has to be stored.
Another often used attribute is -label that allows adding a label to
the data entry widget. Other attributes are available that allow speci‐
fying default values, the expected data types, valid data ranges, etc.
The next example of a more complex argument dialog box provides a good
overview about the different available entry widget types and parameter
attributes. The example contains also some formatting instructions like
-frame and -sep which allows organizing the different entry widgets in
frames and sections:
set ChoiceList {"Choice 1" "Choice 2" "Choice 3" "Choice 4" "Choice 5" "Choice 6"}
set Result [tepam::argument_dialogbox \
-title "System configuration" \
-context test_1 \
-frame {-label "Entries"} \
-entry {-label Entry1 -variable Entry1} \
-entry {-label Entry2 -variable Entry2 -default "my default"} \
-frame {-label "Listbox & combobox"} \
-listbox {-label "Listbox, single selection" -variable Listbox1 \
-choices {1 2 3 4 5 6 7 8} -default 1 -height 3} \
-listbox {-label "Listbox, multiple selection" -variable Listbox2
-choicevariable ChoiceList -default {"Choice 2" "Choice 3"}
-multiple_selection 1 -height 3} \
-disjointlistbox {-label "Disjoined listbox" -variable DisJntListbox
-choicevariable ChoiceList \
-default {"Choice 3" "Choice 5"} -height 3} \
-combobox {-label "Combobox" -variable Combobox \
-choices {1 2 3 4 5 6 7 8} -default 3} \
-frame {-label "Checkbox, radiobox and checkbutton"} \
-checkbox {-label Checkbox -variable Checkbox
-choices {bold italic underline} -choicelabels {Bold Italic Underline} \
-default italic} \
-radiobox {-label Radiobox -variable Radiobox
-choices {bold italic underline} -choicelabels {Bold Italic Underline} \
-default underline} \
-checkbutton {-label CheckButton -variable Checkbutton -default 1} \
-frame {-label "Files & directories"} \
-existingfile {-label "Input file" -variable InputFile} \
-file {-label "Output file" -variable OutputFile} \
-sep {} \
-existingdirectory {-label "Input directory" -variable InputDirectory} \
-directory {-label "Output irectory" -variable OutputDirectory} \
-frame {-label "Colors and fonts"} \
-color {-label "Background color" -variable Color -default red} \
-sep {} \
-font {-label "Font" -variable Font -default {Courier 12 italic}}]
The argument_dialogbox defines all the specified variables with the
entered data and returns ok if the data have been validated via the Ok
button. If the data entry is cancelled by activating the Cancel button,
the argument_dialogbox returns cancel.
if {$Result=="cancel"} {
puts "Canceled"
} else { # $Result=="ok"
puts "Arguments: "
foreach Var {
Entry1 Entry2
Listbox1 Listbox2 DisJntListbox
Combobox Checkbox Radiobox Checkbutton
InputFile OutputFile InputDirectory OutputDirectory
Color Font
} {
puts " $Var: '[set $Var]'"
}
}
-> Arguments:
Entry1: 'Hello, this is a trial'
Entry2: 'my default'
Listbox1: '1'
Listbox2: '{Choice 2} {Choice 3}'
DisJntListbox: '{Choice 3} {Choice 5}'
Combobox: '3'
Checkbox: 'italic'
Radiobox: 'underline'
Checkbutton: '1'
InputFile: 'c:\tepam\in.txt'
OutputFile: 'c:\tepam\out.txt'
InputDirectory: 'c:\tepam\input'
OutputDirectory: 'c:\tepam\output'
Color: 'red'
Font: 'Courier 12 italic'
SEE ALSOtepam::argument_dialogbox(n), tepam::procedure(n)KEYWORDS
argument integrity, argument validation, arguments, entry mask, parame‐
ter entry form, procedure, subcommand
CATEGORY
Procedures, arguments, parameters, options
COPYRIGHT
Copyright (c) 2009/2010, Andreas Drollinger
tepam 0.4.0 tepam(n)
