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IPEP 24: completion and object_info
| Status | Active |
| Author | Min RK <benjaminrk@gmail.com> |
| Created | November 13, 2013 |
| Updated | April 8, 2014 |
| Implementation |
completion and object_info are two messages with Python or IPython-specific remnants,
and we want to improve the situation for these messages with non-Python kernels.
The first problem is that when frontends don't know what language the kernel is in,
lexing becomes untenable.
This is especially challenging for object_info, where an actual object name must be found,
which can include symbols like ?or ! in some languages other than Python.
To address this, we will move lexing to the kernel for messages of this type. Both requests will have two keys:
{
"code" : "multiline\nstring",
# The position of the cursor in the code block.
"cursor_pos" : int,
}Where code is the code context, and The cursor's position (in absolute unicode offset, counting from zero) is cursor_pos.
In the most general case, code might be an entire cell in a notebook (or even the entire notebook),
but it can also be just the line in a line-based interface.
The important point here is that code may be a multiline string.
The full completion request/reply messages are:
complete_request:
content = {
# The (possibly multiline) string context of the completion request.
# This is either the line or entire cell in which the completion is being requested.
"code" : "multiline\nstring",
# The position of the cursor in the code block.
"cursor_pos" : int,
}For example, with the cell:
a = 5
a.is<TAB>the request content would be
{
"code" : "a = 5\na.is",
"cursor_pos" : 10,
}complete_reply:
content = {
# A list of string matches.
"matches" : list,
# the range to be replaced by
"cursor_start" : int,
"cursor_end" : int,
# kernels can add extra information to metadata,
# for use by GUI extensions to affect the display of completions.
"metadata" : dict,
# status should be 'ok' unless an exception was raised during the request,
# in which case it should be 'error', along with the usual error message content
# in other messages.
'status' : 'ok',
}- feedback on matches_extra
object_info_request/reply will be renamed to inspect_request/reply.
An inspect_request message now has the same content as complete_request:
inspect_request:
content = {
# The (possibly multiline) string context of the request.
# This is either the active line or entire cell.
"code" : "multiline\nstring",
# The position of the cursor in the code block.
"cursor_pos" : int,
# The level of detail desired. The default (0) gets most information about the object.
# 1 tries to add the source code of the object.
# In IPython, level 0 is equivalend to 'x?', 1 is equivalent to 'x??'.
"detail_level" : int,
}This is where we still need input from kernel authors
The object_info_reply in 1.x was not just Python specific, but highly IPython-specific.
Since there has been little to no use of the detailed content of the info reply other than simply displaying it,
and given the complexity of proposing language-agnostic inspection fields,
we are deferring to the kernel for formatting and changing object_info_reply to
a mime-bundle message (like display_data).
inspect_reply:
content = {
# status should be 'ok' unless an exception was raised during the request,
# in which case it should be 'error', along with the usual error message content
# in other messages.
"status" : "ok",
# found indicates whether anything was found to inspect.
# If True, data and metadata below will be defined.
"found" : bool,
# the data/metadata keys are interpreted the same as any mime-bundle message
# (display_data, execute_result, etc.)
# a mime-type keyed dictionary of representations of the data
"data" : {"mime/type" : "data"},
# a mime-type keyed dictionary of metadata
"metadata" : {"mime/type" : "metadata"},
}Questions to external kernel authors:
- [ ]: What existing functionality would be lost if structured info replies are removed?