Pipe

The pipe provides a way for the C level to communicate with the script level.

Functions

In C

int mln_lang_ctx_pipe_send(mln_lang_ctx_t *ctx, char *fmt, ...);

This function will send a data set given by ... to a specified script task by ctx.

fmt is used for the interpretation of variable parameters, fmt supports three characters:

• i integer, which should be an mln_s64_t type integer
• r real number, which should be of type double
• s string, which should correspond to the mln_string_t pointer parameter

Return value:

• 0 on success
• -1 on failure

int mln_trace_recv_handler_set(mln_lang_ctx_pipe_recv_cb_t recv_handler);

typedef int (*mln_lang_ctx_pipe_recv_cb_t)(mln_lang_ctx_t *, mln_lang_val_t *);

This function is used to receive data from the script level in C code.

The parameters of recv_handler:

• the first one is the script task context object.
• the second one is the data sent from script level.

Return value:

• 0 on succes
• -1 on failure

In Melang

Pipe(op);

This function is used to subscribe, unsubscribe and receive data from C layer.

op has three values:

• subscribe starts to accept data set.
• unsubscribe stop to accept data set.
• recv receive data set.
• send send data to C level.

Return value:

• nil - not subscribed if call this function with op recv.
• [] - no data received.
• An array with each element in it is also an array.

Example

In C

mln_lang_ctx_pipe_send(ctx, "ir", 1, 3.14);

In Melang

sys = Import('sys');
Pipe('subscribe');
sys.print(Pipe('recv'));
Pipe('unsubscribe');

The output is:

[[1, 3.14], ]