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Update preferred method for reading/writing messages from files

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This commit is contained in:
Jason Paryani
2013-09-01 02:13:19 -07:00
parent eb9e7511d0
commit 6fcdf841e4
7 changed files with 103 additions and 124 deletions
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12
capnp/__init__.py
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@@ -7,9 +7,8 @@ Example Usage::
addressbook = capnp.load('addressbook.capnp')
# Building
message = capnp.MallocMessageBuilder()
addressBook = message.initRoot(addressbook.AddressBook)
people = addressBook.init('people', 1)
addresses = addressbook.AddressBook.newMessage()
people = addresses.init('people', 1)
alice = people[0]
alice.id = 123
@@ -19,16 +18,15 @@ Example Usage::
alicePhone.type = 'mobile'
f = open('example.bin', 'w')
capnp.writePackedMessageToFd(f.fileno(), message)
addresses.writeTo(f)
f.close()
# Reading
f = open('example.bin')
message = capnp.PackedFdMessageReader(f.fileno())
addressBook = message.getRoot(addressbook.AddressBook)
addresses = addressbook.AddressBook.readFrom(f)
for person in addressBook.people:
for person in addresses.people:
print(person.name, ':', person.email)
for phone in person.phones:
print(phone.type, ':', phone.number)

60
capnp/capnp.pyx
View File

@@ -32,7 +32,6 @@ ctypedef double Float64
from libc.stdlib cimport malloc, free
from libcpp cimport bool as cbool
_MAX_INT = 2**63 - 1
ctypedef fused _DynamicStructReaderOrBuilder:
_DynamicStructReader
_DynamicStructBuilder
@@ -131,7 +130,7 @@ cdef class _DynamicListReader:
This class thinly wraps the C++ Cap'n Proto DynamicList::Reader class. __getitem__ and __len__ have been defined properly, so you can treat this class mostly like any other iterable class::
...
person = message.getRoot(addressbook.Person)
person = addressbook.Person.readFrom(file)
phones = person.phones # This returns a _DynamicListReader
@@ -170,10 +169,10 @@ cdef class _DynamicResizableListBuilder:
.. warning:: You need to call :meth:`finish` on this object before serializing the Cap'n Proto message. Failure to do so will cause your objects not to be written out as well as leaking orphan structs into your message.
This class works much like :class:`_DynamicListBuilder`, but it allows growing the list dynamically. It is meant for lists of structs, since for primitive types like int or float, you're much better off using a normal python list and then serializing straight to a Cap'n Proto list. It has __getitem__ and __len__ defined, but not __setitem__.
This class works much like :class:`_DynamicListBuilder`, but it allows growing the list dynamically. It is meant for lists of structs, since for primitive types like int or float, you're much better off using a normal python list and then serializing straight to a Cap'n Proto list. It has __getitem__ and __len__ defined, but not __setitem__::
...
person = message.initRoot(addressbook.Person)
person = addressbook.Person.newMessage()
phones = person.initResizableList('phones') # This returns a _DynamicResizableListBuilder
@@ -184,7 +183,8 @@ cdef class _DynamicResizableListBuilder:
people.finish()
capnp.writePackedMessageToFd(fd, message)
f = open('example', 'w')
person.writeTo(f)
"""
cdef public object _parent, _message, _field, _schema
cdef public list _list
@@ -234,7 +234,7 @@ cdef class _DynamicListBuilder:
This class thinly wraps the C++ Cap'n Proto DynamicList::Bulder class. __getitem__, __setitem__, and __len__ have been defined properly, so you can treat this class mostly like any other iterable class::
...
person = message.initRoot(addressbook.Person)
person = addressbook.Person.newMessage()
phones = person.init('phones', 2) # This returns a _DynamicListBuilder
@@ -278,21 +278,7 @@ cdef class _DynamicListBuilder:
cpdef adopt(self, index, _DynamicOrphan orphan):
"""A method for adopting Cap'n Proto orphans
Don't use this method unless you know what you're doing. Orphans are useful for dynamically allocating objects for an unkown sized list, ie::
message = capnp.MallocMessageBuilder()
alice = m.newOrphan(addressbook.Person)
alice.get().name = 'alice'
bob = m.newOrphan(addressbook.Person)
bob.get().name = 'bob'
addressBook = message.initRoot(addressbook.AddressBook)
people = addressBook.init('people', 2)
people.adopt(0, alice)
people.adopt(1, bob)
Don't use this method unless you know what you're doing. Orphans are useful for dynamically allocating objects for an unkown sized list.
:type index: int
:param index: The index of the element in the list to replace with the newly adopted object
@@ -439,7 +425,7 @@ cdef class _DynamicStructReader:
This class is almost a 1 for 1 wrapping of the Cap'n Proto C++ DynamicStruct::Reader. The only difference is that instead of a `get` method, __getattr__ is overloaded and the field name is passed onto the C++ equivalent `get`. This means you just use . syntax to access any field. For field names that don't follow valid python naming convention for fields, use the global function :py:func:`getattr`::
person = message.getRoot(addressbook.Person) # This returns a _DynamicStructReader
person = addressbook.Person.readFrom(file) # This returns a _DynamicStructReader
print person.name # using . syntax
print getattr(person, 'field-with-hyphens') # for names that are invalid for python, use getattr
"""
@@ -462,7 +448,7 @@ cdef class _DynamicStructReader:
Enums are just strings in the python Cap'n Proto API, so this function will either return a string equal to the field name of the active field in the union, or throw a ValueError if this isn't a union, or a struct with an unnamed union::
person = message.initRoot(addressbook.Person)
person = addressbook.Person.newMessage()
person.which()
# ValueError: member was null
@@ -497,7 +483,7 @@ cdef class _DynamicStructBuilder:
This class is almost a 1 for 1 wrapping of the Cap'n Proto C++ DynamicStruct::Builder. The only difference is that instead of a `get`/`set` method, __getattr__/__setattr__ is overloaded and the field name is passed onto the C++ equivalent function. This means you just use . syntax to access or set any field. For field names that don't follow valid python naming convention for fields, use the global functions :py:func:`getattr`/:py:func:`setattr`::
person = message.initRoot(addressbook.Person) # This returns a _DynamicStructBuilder
person = addressbook.Person.newMessage() # This returns a _DynamicStructBuilder
person.name = 'foo' # using . syntax
print person.name # using . syntax
@@ -601,7 +587,7 @@ cdef class _DynamicStructBuilder:
Enums are just strings in the python Cap'n Proto API, so this function will either return a string equal to the field name of the active field in the union, or throw a ValueError if this isn't a union, or a struct with an unnamed union::
person = message.initRoot(addressbook.Person)
person = addressbook.Person.newMessage()
person.which()
# ValueError: member was null
@@ -620,21 +606,7 @@ cdef class _DynamicStructBuilder:
cpdef adopt(self, field, _DynamicOrphan orphan):
"""A method for adopting Cap'n Proto orphans
Don't use this method unless you know what you're doing. Orphans are useful for dynamically allocating objects for an unkown sized list, ie::
message = capnp.MallocMessageBuilder()
alice = m.newOrphan(addressbook.Person)
alice.get().name = 'alice'
bob = m.newOrphan(addressbook.Person)
bob.get().name = 'bob'
addressBook = message.initRoot(addressbook.AddressBook)
people = addressBook.init('people', 2)
people.adopt(0, alice)
people.adopt(1, bob)
Don't use this method unless you know what you're doing. Orphans are useful for dynamically allocating objects for an unkown sized list.
:type field: str
:param field: The field name in the struct
@@ -814,8 +786,7 @@ cdef class SchemaParser:
addressbook = parser.load('addressbook.capnp')
print addressbook.qux # qux is a top level constant
# 123
message = capnp.MallocMessageBuilder()
person = message.initRoot(addressbook.Person)
person = addressbook.Person.newMessage()
:type file_name: str
:param file_name: A relative or absolute path to a Cap'n Proto schema
@@ -956,7 +927,7 @@ cdef class MessageBuilder:
Don't use this method unless you know what you're doing. Orphans are useful for dynamically allocating objects for an unkown sized list, ie::
addressbook = capnp.load('addressbook.capnp')
m = capnp.MallocMessageBuilder()
alice = m.newOrphan(addressbook.Person)
:type schema: Schema
@@ -1129,8 +1100,7 @@ def load(file_name, display_name=None, imports=[]):
addressbook = capnp.load('addressbook.capnp')
print addressbook.qux # qux is a top level constant in the addressbook.capnp schema
# 123
message = capnp.MallocMessageBuilder()
person = message.initRoot(addressbook.Person)
person = addressbook.Person.newMessage()
:type file_name: str
:param file_name: A relative or absolute path to a Cap'n Proto schema