add python interface design #3964
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doc/design/python_interface.md
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| # Python Interface Design | ||
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| ## Variable as variable data type (not parameter) | ||
| The class Variable is introduced to define the variables that are not parameters. |
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The class Variable is introduced to define the variables, which are not only parameters but also the input data and intermediate outputs.
doc/design/python_interface.md
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| ## Variable as variable data type (not parameter) | ||
| The class Variable is introduced to define the variables that are not parameters. | ||
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| All the variables are defined in a variable scope, `VarScope`, it will check duplicate variable names. |
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It seems that Scope is enough?
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this design is based on current implementation ?
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Not really. This design should handle current implementation and future compile time concepts.
However, is the compile time concept of Scope needs a different name? because in that time, the user cannot access runtime scope directly, so there is only one concept which related to scope in future?
doc/design/python_interface.md
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| The `Variable`'s definition is as follows | ||
| ```python | ||
| class _unique_name_generator: |
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PEP8, class name is upper case
class UniqueNameGenerator(object):
...
doc/design/python_interface.md
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| counter = 0 | ||
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| def __call__(self, prefix): | ||
| name = '%s-%d' % (prefix, counter) |
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Maybe %s.%d is better. Because %s-%d is not a valid filename on some platforms, e.g., Windows.
doc/design/python_interface.md
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| ''' | ||
| var_scope is VarDesc's scope. | ||
| ''' | ||
| self.shape = shape |
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Shape is not stored in Variable. It stored in tensor.
doc/design/python_interface.md
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| name = unique_name_generator("unknown") | ||
| self.name = name | ||
| self.var_scope = var_scope | ||
| if not reuse: |
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It may not be Variable's responsibility to check reuse.
doc/design/python_interface.md
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| g_varscope_stack = [] | ||
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| class VarScope(object): |
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VarScope may not be exposed to users. It should be managed with sub-block or sub-net.
So, let us not write it in this design doc.
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Just some code snippets, not the actual definition. Explain something about a variable scope, no matter what its name is, Scope or VarScope.
Even the original Scope is used, it is better to use a python adapter may be called VarScope so that when we replace Scope easily in Variable latter.
doc/design/python_interface.md
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| So, the parameters should only created in the head of the variable stack, we can implement this stack like | ||
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| ```python | ||
| g_varscope_stack = [] |
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global variables are not good, especially for multi-thread situation.
Maybe we can,
class ScopeStack(object):
def __init__(self):
self.scope = [Scope()]
def push_stack(self):
self.scope.push(Scope())
def pop_stack(self):
self.scope.pop()
def cur_scope(self):
return self.scope[-1]
def global_scope(self):
return self.scope[0]
g_scope_stack = ScopeStack()
# `new_variable` could be based on the `g_scope_stack`, and could be based on a user-defined scope stack.
def new_variable(scope_stack=None):
if scope_stack is None:
scope_stack = g_scope_stack
return scope_stack.cur_scope.new()
doc/design/python_interface.md
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| # Python Interface Design | ||
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| ## Variable as variable data type (not parameter) | ||
| The class Variable is introduced to define the variables, which are not only parameters but also the input data and intermediate outputs. |
There was a problem hiding this comment.
The class Variable is ...
| ''' | ||
| if name is None: | ||
| if prefix is not None: | ||
| name = unique_name_generator(prefix) |
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I like this design. We don't need to call unique_name_generator in layer definitions.
| name = unique_name_generator("unknown") | ||
| self.name = name | ||
| self.var_scope = var_scope | ||
| self.op = op |
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How to define a varibale's op? If two operators write the same variable, which one is its op?
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the last one who write it? @reyoung @jacquesqiao
doc/design/python_interface.md
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| in above example, the `unique_name_generator` is introduced to make unique name with a prefix and can be used to generate variables' and operators' names. | ||
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| ## Scope Stack for Block Inherience | ||
| Each block should has a variable scope that is inheriented from parent's variable scope. |
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should have. 情态动词后不用第三人称单数形式。
| g_scope_stack = ScopeStack() | ||
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| # `new_variable` could be based on the `g_scope_stack`, and could be based on a user-defined scope stack. |
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Users are able to build their own scope stack? What's that for?
No description provided.