关于python：嵌套参数未编译

Nested arguments not compiling

我正试图将我的代码编译成一个python 3模块。当我在空闲状态下选择"运行模块"时，它运行良好，但当我尝试创建分发时，它会收到以下语法错误：

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File"/usr/local/lib/python3.2/dist-packages/simpletriple.py", line 9
def add(self, (sub, pred, obj)):
^
SyntaxError: invalid syntax

有人能帮忙指出语法有什么问题吗？以下是完整的代码：

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import csv

class SimpleGraph:
def __init__(self):
self._spo = {}
self._pos = {}
self._osp = {}

def add(self, (sub, pred, obj)):
"""
Adds a triple to the graph.
"""
self._addToIndex(self._spo, sub, pred, obj)
self._addToIndex(self._pos, pred, obj, sub)
self._addToIndex(self._osp, obj, sub, pred)

def _addToIndex(self, index, a, b, c):
"""
Adds a triple to a specified index.
"""
if a not in index: index[a] = {b:set([c])}
else:
if b not in index[a]: index[a][b] = set([c])
else: index[a][b].add(c)

def remove(self, (sub, pred, obj)):
"""
Remove a triple pattern from the graph.
"""
triples = list(self.triples((sub, pred, obj)))
for (delSub, delPred, delObj) in triples:
self._removeFromIndex(self._spo, delSub, delPred, delObj)
self._removeFromIndex(self._pos, delPred, delObj, delSub)
self._removeFromIndex(self._osp, delObj, delSub, delPred)

def _removeFromIndex(self, index, a, b, c):
"""
Removes a triple from an index and clears up empty indermediate structures.
"""
try:
bs = index[a]
cset = bs[b]
cset.remove(c)
if len(cset) == 0: del bs[b]
if len(bs) == 0: del index[a]
# KeyErrors occur if a term was missing, which means that it wasn't a valid delete:
except KeyError:
pass

def triples(self, (sub, pred, obj)):
"""
Generator over the triple store.
Returns triples that match the given triple pattern.
"""
# check which terms are present in order to use the correct index:
try:
if sub != None:
if pred != None:
# sub pred obj
if obj != None:
if obj in self._spo[sub][pred]: yield (sub, pred, obj)
# sub pred None
else:
for retObj in self._spo[sub][pred]: yield (sub, pred, retObj)
else:
# sub None obj
if obj != None:
for retPred in self._osp[obj][sub]: yield (sub, retPred, obj)
# sub None None
else:
for retPred, objSet in self._spo[sub].items():
for retObj in objSet:
yield (sub, retPred, retObj)
else:
if pred != None:
# None pred obj
if obj != None:
for retSub in self._pos[pred][obj]:
yield (retSub, pred, obj)
# None pred None
else:
for retObj, subSet in self._pos[pred].items():
for retSub in subSet:
yield (retSub, pred, retObj)
else:
# None None obj
if obj != None:
for retSub, predSet in self._osp[obj].items():
for retPred in predSet:
yield (retSub, retPred, obj)
# None None None
else:
for retSub, predSet in self._spo.items():
for retPred, objSet in predSet.items():
for retObj in objSet:
yield (retSub, retPred, retObj)
# KeyErrors occur if a query term wasn't in the index, so we yield nothing:
except KeyError:
pass

def value(self, sub=None, pred=None, obj=None):
for retSub, retPred, retObj in self.triples((sub, pred, obj)):
if sub is None: return retSub
if pred is None: return retPred
if obj is None: return retObj
break
return None

def load(self, filename):
f = open(filename,"rb")
reader = csv.reader(f)
for sub, pred, obj in reader:
sub = unicode(sub,"UTF-8")
pred = unicode(pred,"UTF-8")
obj = unicode(obj,"UTF-8")
self.add((sub, pred, obj))
f.close()

def save(self, filename):
f = open(filename,"wb")
writer = csv.writer(f)
for sub, pred, obj in self.triples((None, None, None)):
writer.writerow([sub.encode("UTF-8"), pred.encode("UTF-8"), obj.encode("UTF-8")])
f.close()

if __name__ =="__main__":
g = SimpleGraph()
g.add(("blade_runner","name","Blade Runner"))
g.add(("blade_runner","name","Blade Runner"))
g.add(("blade_runner","release_date","June 25, 1982"))
g.add(("blade_runner","directed_by","Ridley Scott"))

print list(g.triples((None, None, None)))
print list(g.triples(("blade_runner", None, None)))
print list(g.triples(("blade_runner","name", None)))
print list(g.triples(("blade_runner","name","Blade Runner")))
print list(g.triples(("blade_runner", None,"Blade Runner")))
print list(g.triples((None,"name","Blade Runner")))
print list(g.triples((None, None,"Blade Runner")))

print list(g.triples(("foo","name","Blade Runner")))
print list(g.triples(("blade_runner","foo","Blade Runner")))
print list(g.triples(("blade_runner","name","foo")))

相关讨论

PEP 3113解释了为什么这个特性"tuple参数解包"在python 3中被删除。它还解释了如何移植使用它们的代码。在这种情况下，您需要更改如下函数：

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def add(self, (sub, pred, obj)):
self._addToIndex(self._spo, sub, pred, obj)
self._addToIndex(self._pos, pred, obj, sub)
self._addToIndex(self._osp, obj, sub, pred)

到将元组作为单个参数传递并手动解包的版本：

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def add(self, sub_pred_obj):
sub, pred, obj = sub_pred_obj
self._addToIndex(self._spo, sub, pred, obj)
self._addToIndex(self._pos, pred, obj, sub)
self._addToIndex(self._osp, obj, sub, pred)

对于lambda函数，不能使用赋值进行解包。最好的解决方案通常是不解包。例如，更改此项：

1	lambda (x, y): (y, x)

……

1	lambda xy: (xy[1], xy[0])

对于复杂的函数，这可能会变得很难看，但对于复杂的函数，您可能无论如何都希望使用def它们。

值得注意的是，通过2to3、modernize或futurize运行您的代码，在def和lambda中都会发现这个问题，并准确地提出这些解决方案：

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$ echo 'lambda (x,y): (y,x)' | 2to3 -
--- <stdin> (original)
+++ <stdin> (refactored)
@@ -1 +1 @@
-lambda (x,y): (y,x)
+lambda x_y: (x_y[1],x_y[0])

$ echo -e 'def foo((x,y)):
return (y,x)
' | 2to3 -
--- <stdin> (original)
+++ <stdin> (refactored)
@@ -1 +1 @@
-def foo((x,y)):
+def foo(xxx_todo_changeme):
+ (x,y) = xxx_todo_changeme

如果您试图将python 2.x代码移植到3.x(或双版本代码)，但不了解这两种语言，那么您几乎肯定希望使用这些工具中的一种，或者使用一个封装它们的IDE插件来提供帮助。(尽管您可能不想按原样使用其输出。)