OTPCL pipes up the wazoo. OTPCL treats any command that starts with a
pipe character (
|) as a command terminator - that is, it'll treat all the
words before it as one command, then resume command parsing. This is a bit
tricky to describe in English, so it's easier to just show you that this:
foo | bar | baz
...is equivalent to this:
foo | bar | baz
In this case, the
| happens to take the return value of the
previously-executed command (i.e. the
$RETVAL variable) and pass it as the
first argument to the command named in its own first argument. That is, both
of the above are equivalent to this:
baz [bar [foo]]Of course, the command doesn't necessarily have to do this sort of chaining (or even pay attention to
$RETVALat all), but OTPCL's pipe support exists specifically to facilitate this sort of pattern, as exemplified by the various commands defined in this here module.
|'|#*'/2||"Insert Splat" operator.|
|'|&'/2||"And Also" operator.|
|'||'/2||"Or Else" operator.|
'|!'(X1, State) -> any()
"Send" operator. Send the previous command's return value to the specified process.
'|#'(Args, State) -> any()
"Insert" operator. Splits its arguments at the specified position, inserts the previous command's return value between them, and invokes the resulting list of words as a command. That is:
foo |# 0 bar baz # -> [foo] bar baz foo |# 1 bar baz # -> bar [foo] baz foo |# 2 bar baz # -> bar baz [foo]Note that, for obvious reasons, trying to insert an argument into a position greater than the number of existing arguments will result in an error.
'|#*'(Args, State) -> any()
"Insert Splat" operator. Like
|#`, but expands the previous commands
return value during insertion (instead of just inserting the list as a single
'|&'(Args, State) -> any()
"And Also" operator. If the previous command returned a "truthy" value, run the arguments as a command.
'|*'(Args, State) -> any()
"Splat" operator. If the previous command returned a list, and there are no words after the "splat", then treat the first element as a command name, the rest as its arguments, and run it. Else, treat the first argument as the command name, pass the list elements as arguments, then pass any other passed arguments as additional arguments, then run the resulting command.
'||'(Args, State) -> any()
"Or Else" operator. If the previous command returned a non-"truthy" value, run the arguments as a command.
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