Unimplemented Options And Constants

PycURL intentionally does not expose some of the libcurl options and constants. This document explains libcurl symbols that were omitted from PycURL.

*DATA options

In libcurl, the *aDATA options set client data for various callbacks. Each callback has a corresponding *DATA option.

In Python - a language with closures - such options are unnecessary. For example, the following code invokes an instance’s write method which has full access to its class instance:

class Writer(object):
    def __init__(self):
        self.foo = True

    def write(chunk):
        # can use self.foo

writer = Writer()
curl = pycurl.Curl()
curl.setopt(curl.WRITEFUNCTION, writer.write)

As of version 7.19.3, PycURL does implement three *DATA options for convenience: WRITEDATA, HEADERDATA and READDATA. These are equivalent to setting the respective callback option with either a write or read method, as appropriate:

# equivalent pairs:
curl.setopt(curl.WRITEDATA, writer)
curl.setopt(curl.WRITEFUNCTION, writer.write)

curl.setopt(curl.HEADERDATA, writer)
curl.setopt(curl.HEADERFUNCTION, writer.write)

curl.setopt(curl.READDATA, reader)
curl.setopt(curl.READFUNCTION, reader.read)


It is unclear how the SSL context should be exposed to Python code. This option can be implemented if it finds a use case.

Undocumented symbols

Some symbols are present in libcurl’s symbols in versions document but are not documented by libcurl. These symbols are not implemented by PycURL.

As of this writing, the following symbols are thusly omitted: