Variables

To support a programming language for macro definitions (p. ) stedi is equipped with the possibility to define and use variables. The syntax that is connected to the use of these variables resembles the syntax of the UNIX c-shell csh very much. When variables are used their name is preceded by a dollar ($) sign. The name of the variable should consist of alphanumeric characters of which the first should be alphabetic. In addition the underscore may be used at any position (also the first). There may be no more than 10 characters (the dollar sign doesn't count). If the use of the variable makes it necessary that the contents of the variable are immediately followed by an alphanumeric character the name may be enclosed in curly brackets: ${name}. The use of names is case sensitive as this doesn't interfere with the file system. There is a number of reserved names with a special meaning. These are given later in this chapter.

When a variable is defined or a value is assigned to it its occurrence at the left hand side of the statement shouldn't be preceded by the dollar sign. The syntax of such a statement is:

    set variable = expression

If the variable exists already its old `value' is replaced by its new `value'. If the variable didn't exist a new entry in the list of variables is made. If this is originated from inside a macro, the variable is removed from the list again when the macro is terminated. There are two options for the set command. The global option makes that for an already existing value the editor looks also among the variables of the parents (and these can be changed) This is done with

    set -G variable = expression

The local mode makes that the editor will not look among the variables of the parents and won't change these. If there is no variable yet by this name among the variables of the macro a new one will be made, even if this means that there is now more than one variable with that name. If a child process looks for a variable with this name it will run into the closest variable. The local mode (the default mode) is forced with the command:

    set -L variable = expression

The L and the G are case insensitive. The effect of this is that a macro has full control over the variables of its parents, but all variables of its children are hidden from it. The syntax of the expression at the right hand side is explained in the chapter on macros (p. ). If just a simple string is needed it can be provided, enclosed by double quotes:

	set quotation = "Eureka!"

If a dollar sign is needed inside the string this can be done by `escaping' it with a backslash character. The other character that should be escaped this way is the double quote. In addition linefeeds can be put in the string by an escape character (or a backslash for systems that don't use the backslash in the file system) at the end of the line. In this last case a linefeed is put in the string and the next statement is seen as a continuation. The matching double quote should then be on this next line. In the command line a linefeed or carriage return can always be inserted after typing an escape character, or with the Ctrl-H command (p. )

The `value' of a variable is always a character string. For some purposes stedi will try to interpret this string as a number. If this turns out to be impossible an error message may be the result. Some operations can give different results, depending on whether the variables involved can be interpreted numerically (p. .

The contents of a variable can be inspected with the show command. This command has the syntax:

    show variable

In this command the dollar sign should not be used in front of the variable. You can try this out with the statements:

    show date

and

    show $date

In the second case the date is substituted before the show command is executed. This means that there is a rather funny name that doesn't obey the rules for names, so an error message will be given.

There are names that have a special meaning. Most of these give the user access to internal information so that he may use it inside macro's. Others are meant to control some settings of stedi. In addition the variables in the environment can be inspected.

The reserved names concerning the internal information are:

buffer

The number of the current buffer.

byte

The number of bytes in the file before the cursor position.

char

The current character. An empty string when the cursor is in virtual space.

column

The number of the column of the cursor in the current buffer.

cwd

The name of the current working directory. This is usually the name of the directory from which the editor was started.

date

The date.

direction

Either '<', '<<', '0', '>>' or '>' for the search/replace direction modes.

filename

The name of the file in the current buffer. Only its local name is considered.

fold

The name of the current fold if the current fold would be closed.

fullname

The full name of the file in the current buffer. This name includes the path name.

insertmode

Either an 'I' or an 'O' for the insert or overstrike modes.

isfold

This variable indicates whether the cursor is in a closed fold line.

ismark

The value ON indicates that there is a mark. If there is no mark the value is OFF.

key

The use of this variable causes stedi to wait for a character from the keyboard. The character is presented as a string of 8 hexadecimal digits in the same notation as the key that is entered in the text after a ctrl-K.

lastmess

The last message that was displayed in the message line. This could be used for analysis to make the editor jump to an error message of the macro processor.

line

The number of the current line in the current buffer.

linechars

The number of characters in the current line.

maxcol

The number of the column if the cursor were to be moved to the end of the current line.

nextatt

The file attribute of the file that was obtained after $nextfile has returned the value true. See also p. .

nextdate

Gives the date and time of the last file that was found with $nextfile. The format is yyyy/mm/dd-hh:mm:ss to allow for lexicographic sorting of dates. See also p. .

nextfile

When this variable is read it returns true (the digit 1) if in the file search that was initiated with a `first' command a new file was found. Each use of $nextfile tries to find a new file. If no new file is found the value false (a digit 0) is returned. The information about the file can be obtained with the variables nextatt, nextdate, nextname and nextsize. See also p. .

nextfname

Gives the name of the last file that was found with $nextfile. If the pattern given the the `first' statement contained any path information it is included in the name. See also p. .

nextname

Gives the name of the last file that was found with $nextfile. There is no path information in this name. See also p. .

nextsize

Gives the size of the last file that was found with $nextfile. See also p. .

numchar

The number of characters left of the cursor.

range

This variable contains the characters of the current line that are between the column of the mark and the column of the cursor. It doesn't matter whether the mark is in the same line as the cursor. Only its column position is relevant.

returncode

The string that was set in the last return statement that the editor encountered. If a return statement doesn't mention a return code or when there is no return code the string is empty.

screenline

The number of the line on the screen in which the cursor is.

searchmode

Either an 'S' or an 'N' for the case sensitive or case non sensitive search mode.

shell

Indicates whether there is a command shell present that can accept commands via the ! command. On the PC-like computers this means that the environment variable COMSPEC has been set.

totlines

The total number of lines in the current buffer.

word

The current word.

wordwrap

The size of the word wrap. This will be an empty string when the word wrap is either off or in the fortran mode.

writemode

The character that indicates in which mode stedi would write the contents of the current buffer it it would be written (A, P, R or U).

wword

The current word in the wordwrap sense. This means a word that is enclosed by the white space characters blank, tab or ASCII zero, rather than the more sophisticated definition for the variable `word'.

yankbuf

Indicates the current yank buffer with either 'Y' or 'y'.

The above variables should not be used in the left side of a `set' command. If the user tries to set such a variable a new variable with this name is made and the old meaning of it is lost until the variable is removed again. One can experiment with the above variables by using the show command as in

    show cwd

to see what the current directory is.

The variables that are meant to control some of the settings of stedi are:

autoclose

Value is "on" or "off". determines whether the autoclose facility is used when files are read or written.

backup

The character of the current backup mode (b, B, V or a ! indicating that no backup is made).

color

Indicating whether the colors of the text screen and the message line should be exchanged. Values are "on" or "off". See also the Alt-C command (p. ).

dirty

Value is "on" or "off", depending on whether the dirty flag is on or off. The dirty flag indicates whether the file has been modified. It is displayed as one of the status characters.

hstep

The stepsize for horizontal scrolling in the text buffers.

maxhist

The maximum number of lines in the command line history.

menuspaced

Determines whether only every odd position in the menu bar is sensitive to clicks.

mstep

The stepsize for scrolling in the command/message line.

numbers

Sets the updating of the line number in the status line "on" or "off". This is mainly for terminal connections. For those the regular updates of the line number can mean a significant slowdown.

pagedelay

This variable has a numeric value which is the number of milliseconds that stedi will take at least for drawing one screen when scrolling with shift-up or shift-down (page-up or page-down).

waitflag

Sets the wait flag on or off. This flags determines whether after the execution of an external program or a call to shell stedi will wait for a key to be pressed. This waiting avoids disturbing the screen before the user has read it. See also the chapter on executing an external command p. .

<char>

The character can be any single character. The value assigned is "on", "off" or "single". When "on" it forces the indicated character to be interpreted as belonging to words. If the value is "off" it will never be seen as part of a word and the value "single" makes the character into a single character word. See also the chapter on Word-oriented commands p. .

These variables can be set and their settings can be stored in the default file (with the exception of `dirty').

If a variable is used which has not been defined by the user, and whose name isn't one of the reserved names stedi will inspect the environment (p. ). If there is an environment variable of which the name matches the name of the searched for variable in a case insensitive way the return value will be the contents of the environment variable. This way one can for instance test for the setting of the environment variable STEDIMAC etc.

The number of variables that can be used in stedi is limited only by the size of the available memory. The same mechanism that is used to store the lines in the text is also used to store the variables. This has an advantage and a disadvantage: The advantage is that no fixed size buffers for names have to be allocated at startup (so that space isn't lost). The disadvantage is that it is impossible to do a binary or hashed search for a name, so that when there are very many variables searching for a name may become slow (everything is relative).