PyUNO usability improvements
Matthew J. Francis
mjay.francis at gmail.com
Sun Jun 14 06:26:43 PDT 2015
Hi,
For the past few weeks I've been working on some upgrades to PyUNO,
which have now reached (what I hope is) a sufficient level of sanity and
stability. I've pushed the changes to:
https://gerrit.libreoffice.org/16272
Given that this is a fairly large API change (if for a scripting
language that is not -yet- heavily used by our users), it probably
needs a careful review, but I have a suspicion that probably no one
developer currently has knowledge of all the interlocking requirements
at play here - or PyUNO might look somewhat different to begin with ;)
If anyone feels kind enough to take on the work of reviewing this,
please give me a shout and I'll offer what help I can on understanding
how all the pieces fit together.
* Parts of the test suite depend on
https://gerrit.libreoffice.org/16073
Without this fix, various of the tests will fail
Regards
Matthew Francis
------------------------------------------------------------------------
Make PyUNO provide more Pythonic behaviour
- Simplifies working with UNO objects by giving the behaviour of
Python lists, dicts and iterators to objects which implement UNO
container interfaces
- Applies a custom behaviour to allow objects which implement
com::sun::star::table::XCellRange to yield cells and cell ranges by
subscript
- When UNO container objects are addressed in the new style,
eliminates the requirement to manually construct Any objects for
contained elements which are typed sequences
- Allows lists and iterators to be passed wherever a UNO method
accepts a sequence
- Relaxes the requirements for initialising UNO structs to allow
some members to be skipped when all initialisers are passed by name
1. Collection interfaces
========================
Objects which implement core UNO collection interfaces are made to
behave in a way that is more natural for Python code.
com::sun::star::container::XIndexAccess
com::sun::star::container::XIndexReplace
com::sun::star::container::XIndexContainer
- Objects provide Python list access semantics
num = len(obj) # Number of elements
val = obj[0] # Access by index
val1,val2 = obj[2:4] # Access by slice
val1,val2 = obj[0:3:2] # Access by extended slice
if val in obj: ... # Test value presence
for val in obj: ... # Implicit iterator (values)
itr = iter(obj) # Named iterator (values)
obj[0] = val # Replace by index
obj[2:4] = val1,val2 # Replace by slice
obj[0:3:2] = val1,val2 # Replace by extended slice
obj[2:3] = val1,val2 # Insert/replace by slice
obj[2:2] = (val,) # Insert by slice
obj[2:4] = (val,) # Replace/delete by slice
obj[2:3] = () # Delete by slice (implicit)
del obj[0] # Delete by index
del obj[2:4] # Delete by slice
com::sun::star::container::XNameAccess
com::sun::star::container::XNameReplace
com::sun::star::container::XNameContainer
- Objects provide Python dict access semantics
num = len(obj) # Number of keys
val = obj[key] # Access by key
if key in obj: ... # Test key presence
for key in obj: ... # Implicit iterator (keys)
itr = iter(obj) # Named iterator (keys)
obj[key] = val # Replace by key
obj[key] = val # Insert by key
del obj[key] # Delete by key
com::sun::star::container::XEnumerationAccess
- Objects provide Python iterable semantics
for val in obj: ... # Implicit iterator
itr = iter(obj) # Named iterator
com::sun::star::container::XEnumeration
- Objects provide Python iterator semantics
for val in itr: ... # Iteration of named iterator
if val in itr: ... # Test value presence
Objects which implement both XIndex* and XName* are supported, and
respond to both integer and string keys. However, iterating over
such an object will return the keys (like a Python dict) rather than
the values (like a Python list).
2. Cell ranges
==============
A custom behaviour is applied to objects which implement
com::sun::star::table::XCellRange to allow their cells and cell
ranges to be addressed by subscript, in the style of a Python list
or dict (read-only). This is applicable to Calc spreadsheet sheets,
Writer text tables and cell ranges created upon these.
cell = cellrange[0,0] # Access cell by indices
rng = cellrange[0,1:2] # Access cell range by index,slice
rng = cellrange[1:2,0] # Access cell range by slice,index
rng = cellrange[0:1,2:3] # Access cell range by slices
rng = cellrange['A1:B2'] # Access cell range by descriptor
rng = cellrange['Name'] # Access cell range by name
Note that the indices used are in Python/C order, and differ from
the arguments to methods provided by XCellRange.
- The statement cellrange[r,c], which returns the cell from row r
and column c, is equivalent to calling
XCellRange::getCellByPosition(c,r)
- The statement cellrange[t:b,l:r], which returns a cell range
covering rows t to b(non-inclusive) and columns l to r(non-
inclusive), is equivalent to calling
XCellRange::getCellRangeByPosition(l,t,r-1,b-1).
In contrast to the handling of objects implementing XIndex*,
extended slice syntax is not supported. Negative indices (from-end
addresses) are supported only for objects which also implement
com::sun::star::table::XColumnRowRange (currently Calc spreadsheet
sheets and cell ranges created upon these). For such objects, the
following syntax is also available:
rng = cellrange[0] # Access cell range by row index
rng = cellrange[0,:] # Access cell range by row index
rng = cellrange[:,0] # Access cell range by column index
3. Elimination of explicit Any
==============================
PyUNO has not previously been able to cope with certain method
arguments which are typed as Any but require a sequence of specific
type to be passed. This is a particular issue for container
interfaces such as XIndexContainer and XNameContainer.
The existing solution to dealing with such methods is to use a
special method to pass an explicitly typed Any, giving code such as:
index = doc.createInstance("com.sun.star.text.ContentIndex");
...
uno.invoke( index.LevelParagraphStyles , "replaceByIndex",
(0, uno.Any("[]string", ('Caption',))) )
The new Pythonic container access is able to correctly infer the
expected type of the sequences required by these arguments. In the
new style, the above call to .replaceByIndex() can instead be
written:
index.LevelParagraphStyles[0] = ('Caption',)
4. List and iterator arguments
==============================
Wherever a UNO API expects a sequence, a Python list or iterator can
now be passed. This enables the use of list comprehensions and
generator expressions for method calls and property assignments.
Example:
tbl = doc.createInstance('com.sun.star.text.TextTable')
tbl.initialize(10,10)
# ... insert table ...
# Assign numbers 0..99 to the cells using a generator expression
tbl.Data = ((y for y in range(10*x,10*x + 10)) for x in range(10))
5. Tolerant struct initialisation
=================================
Previously, a UNO struct could be created fully uninitialised, or by
passing a combination of positional and/or named arguments to its
constructor. However, if any arguments were passed, all members were
required to be initialised or an exception was thrown.
This requirement is relaxed such that when all arguments passed to a
struct constructor are by name, some may be omitted. The existing
requirement that all members must be explicitly initialised when
some constructor arguments are unnamed (positional) is not affected.
Example:
from com.sun.star.beans import PropertyValue
prop = PropertyValue(Name='foo', Value='bar')
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