The callback returns the number of elements in the buffer that have been filled and are ready to send. The special value .abortRequest can be returned in order to abort the current request. The special value .pauseRequest can be returned in order to pause the current request.
import std.net.curl; string msg = "Hello world"; auto client = HTTP("dlang.org"); client.onSend = delegate size_t(void[] data) { auto m = cast(void[]) msg; size_t length = m.length > data.length ? data.length : m.length; if (length == 0) return 0; data[0 .. length] = m[0 .. length]; msg = msg[length..$]; return length; }; client.perform();
The event handler that gets called when data is needed for sending. The length of the void[] specifies the maximum number of bytes that can be sent.