The [regPrefixChar] command

This file documents the new [regPrefixChar] command as of version 8.2a1d5 of AlphaX.

• the -regexp argument is required. It specifies, by the means of a regular expression expr, the values among which the infix can be chosen. For instance, if we wanted to allow any digit between 0 and 5 and the letters a, b, c, the value of the option would be

 
[0-5abc]

If the user did not enter any number or character recognized as an infix and pressed ctrl-B S directly then the argument appended to the proc would be empty.

(:title The [regPrefixChar] command:)

This file documents the new [regPrefixChar] command as of version 8.2a1d5 of AlphaX. This is an experimental command proposed as a part of the bindings reform. It is open to discussion.

Introduction

The [regPrefixChar] command lets you define composite bindings involving an infix. For instance, the Embrace package implements complex bindings like ctrl-B 3 S: here B is the prefix, 3 is the infix and S is the suffix (or key combo). Such a binding means that the user has to press the ctrl-B key combo, then press 3 and then press S. The result of this action, as implemented by the the Embrace package, is that the 3 preceding words are enclosed in a pair of square brackets.

The new [regPrefixChar] command lets you specify a regular expression defining the permitted values for the infix.

Synopsis

The syntax of the [regPrefixChar] command is

     regPrefixChar -regexp expr ?-prompt str?

The arguments have the following meaning:

• the -regexp argument is required. It specifies, by the means of a regular expression expr, the values among which the infix can be chosen. For instance, if we wanted to allow any digit between 0 and 5 and the letters a, b, c, the value of the option would be ((| [0-5abc] |))
• the -prompt argument is optional. It specifies the text of the prompt string written in the status bar as a label for the input field. If it is not specified, the prefix combo (for instance ctrl-B in the preceding example) is used as a default.

Concerning the infix, the following rules apply: in the case digits are allowed by the regular expression, it is possible to enter several digits in a row, that is to say to compose numbers, before the key combo. Otherwise the infix is a single character. For instance, in the example above, the infix could be either a number composed of digits between 0 and 5 (like 1, 20, 54321, etc.) or one of the letters a, b, or c.

Howto

Here is an example to demonstrate how the command works. Say we want to define a complex binding like

 
     ctrl-B infix S

where infix is iether a number or the letter r.

Note that this example makes use of the new [binding] command introduced

for more details about it.

The ctrl-B prefix combo must be bound to the [regPrefixChar] command (instead of the simple [prefixChar] command used to create composite bindings without an infix):

     binding create {z 'B'} {regPrefixChar -regex {[0-9r]}}

The regular expression [0-9r] specifies that the infix can be either a number or the letter r. It could also be written as (\d|r).

Now, when the user presses ctrl-B, AlphaX will be expecting the infix followed by the key combo (the letter S in this example). As soon as the S is entered, AlphaX invokes the proc associated with the binding after appending the infix to the list of arguments. For instance, if the user entered ctrl-B 15 S, the proc would be invoked as

with the result that the 15 preceding words will be enclosed in a pair of brackets.

(add your comments here...)

     binding create {z 'B'} numPrefixChar

This file documents the new [numPrefixChar] command as of version 8.2a1d5 of AlphaX. This is an experimental command proposed as a part of the bindings reform. It is open to discussion.

This example makes use of the new [binding] command also introduced in version 8.2a1d1 of AlphaX. See the BindingCommand page for more details about this command.

The action triggered by the combo is a Tcl proc or a Tcl script. The composite binding is defined with the [binding] command and takes the Tcl script as its last argument. For instance:

     binding create -prefix {z 'B'} {"" 'S'} {embrace::toggle "\[" "\]"}]

The simple ctrl-B combo must be bound to the new [numPrefixChar] command instead of [prefixChar]:

     binding create {z 'B'} prefixChar

(add your comments here...)

(:title The [numPrefixChar] command:)

This file documents the new [numPrefixChar] command introduced in version 8.2a1d1 of AlphaX. This is an experimental command proposed as a part of the bindings reform. It is open to discussion.

The [numPrefixChar] command lets you define composite bindings

The new [numPrefixChar] command simplifies the definition

This example makes use of the new [binding] command also introduced in version 8.2a1d1 of AlphaX. See the BindingCommand page for more details about this command.

The simple ctrl-B combo must be bound to the new [numPrefixChar] command

     set countAction [action create -script "numPrefixChar"]

(possibly several digits) and a non-digit keypress (the letter S in this example). As soon as the S is

type default (argument with a default value). For instance

(add your comments here...)

Here is an example to demonstrate how it works. Say we want to define a

(possibly several digits) and a non-digit keypress (the letter S in our example). As soon as S is

type default (argument with a default value). For instance

(:title The [countedPrefixChar] command:)

This file documents the new [countedPrefixChar] command introduced in version 8.2a1d1 of AlphaX. This is an experimental command proposed as a part of the bindings reform. It is open to discussion.

The [countedPrefixChar] command lets you define composite bindings which expect a number to be entered before an action is triggered. For instance, the Embrace package implements complex bindings involving an infix, like ctrl-B 3 S. Such a binding means that the user has to press the ctrl-B key combo, then press 3 and then press S. The result is that the 3 preceding words are enclosed in a pair of square brackets.

Until now, in order to obtain such a behavior, one had to implement a series of bindings involving the [prefixChar] command. This technique allows only for a limited set of values for the number (currently the Embrace package installs bindings for values 1 to 5).

The new [countedPrefixChar] command simplifies the definition of bindings with an infix number and removes the limitation: it is now possible to enter any value for the infix number.

Here is an example to demonstrate this works. Say we want to define a complex binding like

 
     ctrl-B num S

where num is any integer value. This example makes use of the new [action] and [binding] commands also introduced in version 8.2a1d1 of AlphaX. See the ActionCommand and BindingCommand pages for more details about these commands.

The action triggered by the combo must be defined with the [action] command. For instance:

 
     set theAction [action create -script {embrace::toggle "\[" "\]"}]

The composite binding is defined with the [binding] command and takes the action token as its last argument:

 
     binding create -prefix {z 'B'} {"" 'S'} $theAction

The simple ctrl-B combo must be bound to the new [countedPrefixChar] command instead of [prefixChar]:

 
     set countAction [action create -script "countedPrefixChar"]
     binding create {z 'B'} $countAction

Now, when the user presses ctrl-B, AlphaX will be expecting a number (possibly several digits) and the letter S. As soon as the letter S is entered, AlphaX invokes the proc associated with the action after appending the entered value to the list of arguments. For instance, if the user entered ctrl-B 15 S, the proc would be invoked as

 
     embrace::toggle "\[" "\]" 15

If the user did not enter any number and pressed ctrl-B S directly then no additional argument would be appended to the proc. This implies that the proc's last argument, representing the infix, be of type default. For instance

 
     proc fooActionProc {arg1 arg2 ... {infix ""} } {
         # definition
     }

(add your comments here...)