C-style functions
C-style functions
Inlined commands for expressions and statements
Description
The traditional way to spawn a sub-shell would be ${}
(or $()
in Bourne Shell and its many derivatives). This works great for inlining entire command lines but it isn't so convenient if you want to call one command and particularly within an expression.
This is where C-style functions can be more ergonomic. They follow the common structure of command(parameters...)
. For example:
» out("hello world")
The syntax is not exactly like C and its derivatives however:
- parameters are white space delimited, like with command line statements
- strings do not need to be quoted, like with command line statements
And unlike statements:
- you cannot redirect stdout nor stderr
- stdout is never a TTY. Even when it is ran directly in the terminal, it is still treated as a sub-shell
Ostensibly, C-style functions are just syntactic sugar for ${}
. As such, they're not intended to be used liberally but rather just in instances it improves readability.
Examples
Assignment In Expressions
As a C-style function (CSF) vs a sub-shell:
# CSF
» $doc = open(README.md)
# Sub-shell
» $doc = ${open README.md}
Numeric Value In Expressions
As a C-style function (CSF) vs a sub-shell:
# CSF
» datetime(--in {now} --out {unix}) / 60
28687556.3
# Sub-shell
» ${datetime --in {now} --out {unix}} / 60
28687556.3
Statement Inlining
As a C-style function (CSF) vs a sub-shell:
# CSF
» echo It is datetime(--in {now} --out {py}%H) o\' clock
It is 23 o' clock
# Sub-shell
» echo It is ${datetime --in {now} --out {py}%H} o\' clock
It is 23 o' clock
Notice in the example above, echo
's parameters are not quoted. This is because C-style functions do not support infixing.
Detail
Valid Function Names
Please note that currently the only functions supported are ones who's names are comprised entirely of alpha, numeric, underscore and/or exclamation marks.
String Infixing
C-style functions do not support being infixed like sub-shells can be:
# CSF
» echo "It is datetime(--in {now} --out {py}%H) o\' clock"
It is datetime(--in {now} --out {py}%H) o' clock
# Sub-shell
» echo "It is ${datetime --in {now} --out {py}%H} o\' clock"
It is 23 o' clock
See Also
- Language Tour: Getting started with Murex
datetime
: A date and/or time conversion tool (likeprintf
but for date and time values)echo
: Print a string to the stdout with a trailing new line characterexpr
: Expressions: mathematical, string comparisons, logical operatorsopen
: Open a file with a preferred handler- sub-shell:
This document was generated from gen/parser/c-style-functions_doc.yaml.