declarations: Parameter/variable declarations

Package: language

Syntax

vartype [*]varname[index_list] [= init_value] [{options}] [, ...]

  or

vartype [*]varname[index_list] [{init_value [, options]}] [, ...]

Elements

vartype: One of the legal variable types, i.e.: int, bool, char, real, gcur, imcur, struct, file

varname: The name of the variable or parameter. The name must begin with an alphabetic character or '_' and should be fewer than 64 characters in length. If the name is preceded by a '*', then the variable is 'list-directed', meaning that a new value is taken from a list each time the parameter is read.

index_list: The index_list consists of a series of ranges enclosed in square brackets. A range may be a single integer in which case the range is from 1 to that integer, or two integers separated by a colon. The second integer must be larger than the first. Ranges are separated by commas. In the special case that no ranges are specified by the user, the variable is assumed to be a one-dimensional array with a range from 1 to the number of elements in the initialization list.

init_value: The initialization value is a single value for scalar parameters but may be a list for array. A repetition count may be specified in the form rep_count (value) which is equivalent to value repeated the rep_count times. The values in the initialization list are separated by commas.

options

Options define certain characteristics of the variables. Each options has the form opt_name=value where value is a constant. The current options are:

mode: Determines whether the parameter is queried for and whether it is learned after task execution. The default mode for parameters declared in the argument list of a CL procedure is "a", and "h" otherwise.

min: The minimum allowable value for the parameter. If omitted, no min checking is performed.

max: The maximum allowable value for the parameter. If omitted, no max checking is performed.

prompt: The prompt to be used when the parameter is queried for.

enum: The set of allowable string values for a string valued parameter. The character '|' delimits successive enumerated strings.

filetype

For a file type parameter, a string containing characters giving file characteristics to be checked for when the file parameter is used.

r       file exists and is readable
w       file exists and is writable
n       file does not exist
b       file is a binary file
t       file is a text file

length: For a string type parameter, the number of characters of storage to allocate for the string. If the actual length of a string later exceeds the allocated value the string will be silently truncated.

Note that all string constants in an options list must be enclosed in quotes.

Description

Declaration statements are used for inline declaration of parameters and local variables. A declaration after the begin statement of a procedure script is a declaration of a local variable, but any other declaration defines a parameter. Parameters are generally saved between invocations of a script while local variables are not.

Parameter and variable declarations should always precede executable statements with a script. Certain functions are legal before declarations, but this depends upon certain hidden aspects of declarations which are not obvious to the user.

Examples

real    x
int     ii=32
int     y {min=0, max=14}
char    z="abc" {enum="abc|def|ghi", mode="q"}

bool    isotest {YES, mode="ql",
            prompt="Do you want to test for isotropy?"}

int     ii=1 {min=0,max=10, prompt="Number of images", mode="h"}
file    infile="testfile" {filetype="r"}
struct  line {length=80, mode="h"}

real    array[10]
int     iarray[15]=1,2,3,4,5,6,7,8,9,10,11,12,13,14,15 {min=0, max=100}
int     jarray[15] { 5(0), 5(2), 5(4), min=0, max=400}
char    carray[5]= 5("Junk")
bool    flags[4,-3:3] = 28(NO) {mode="h", prompt="Value set"}
file    inp_files[3]= "fil1.inp", "fil2.inp", "fil3.inp"

int     karray[3]=1     # (note second and third elements are undefined)
struct  *list="inputfile.list" {mode="q"}
int     *ilist="infile.inp" {mode="h", min=0, max=100}

Bugs

Options are only permitted for parameters, not local variables.
The filetype options are recognized but are not implemented internally.