NAME¶

call-handler - (service-processing program-flow)

PURPOSE¶

Call another handler within the same process.

SYNTAX¶

call-handler <request path> [ return-value  <return value> ]

DESCRIPTION¶

Calls another handler within the same request in the same process. You can call any handler within the same application. "Calling a handler" means executing it solely within the context of the top handler currently running; no before-handler or after-handler will execute for the called handler.

<request path> is the request path served by the handler being called. It can be a string variable or a constant.

Use set-param and get-param to pass parameters between the caller and callee handlers.

You can obtain a <return value> from the called handler <request path> by using "return-value" clause. See return-handler on how to return a number value from <request path> handler.

call-handler uses the same high-performance hash table used by a request to route requests by name; if <request path> is a constant string, then a hash table lookup is performed only once for the life of the process and all subsequent calls use a cached address of the request handler.

EXAMPLES¶

The following example demonstrate calling a call-handler twice, and also using its output inline in the caller. An input parameter is passed to it, and an output obtained:

Copy to file "callsub.golf":

%% /callsub public


    //


    // First call to call-handler


    //


    // Set input for call-handler


    set-param inp = "some string"


    (( s


    call-handler "/sub/service"


    ))


    // Get output from call-handler


    get-param out type string


    @<<print-out s>> with output [<<print-out out>>]


    //


    // Second call to call-handler


    //


    // Set input for call-handler called as inline code


    set-param inp = "new string"


    (( s


    @Output: <<call-handler "/sub/service">>


    ))


    // Get output from call-handler


    get-param out type string


    @<<print-out s>> with output [<<print-out out>>]
%%

And in "sub/service.golf" file (meaning file "service.golf" in subdirectory "sub"):

%% /sub/service private


    @This is sub!


    get-param inp


    (( out


    @got input: <<print-out inp>>


    ))


    set-param out = out
%%

Create and build an application:

gg -k subhandler
gg -q

Run it:

gg -r --req="/callsub" --exec --silent-header

The output:

This is sub! with output [got input: some string]
Output: This is sub! with output [got input: new string]

SEE ALSO¶

Program flow

break-loop call-handler code-blocks continue-loop do-once exit-handler if-defined if-true quit-process return-handler start-loop
Service processing

after-handler before-handler begin-handler call-handler See all documentation