blocks|key|5339863|text|正确的方法是从xml中知道每种类型应该是什么。这将防止碰巧是数字字符串的东西以int结尾，等等。但假设这是不可能的。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|5339864|对于int类型，我更喜欢|5339865|if+value.isdigit():
++++val+=+int(value)|code-block|syntax|javascript|5339866|对于日期，我能想到的唯一另一种方法是拆分它并查看各个部分，这将比让strptime引发异常更混乱。|5339867|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|N|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|O|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|P|8|@]|9|@]|A|$]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

The right way would be to know from the xml what type each should be. This would prevent things that happen to be numeric strings from ending up as an int, etc. But assuming that isn't possible.

for int type I prefer 

<pre><code>if value.isdigit():
 val = int(value)
</code></pre>

for the date, the only other way I can think of would be splitting it and looking at the parts, which would be messier then just letting the strptime raise an exception.

blocks|key|5339891|text|def+normalize_availability(value):
++++"""
++++Normalize+the+availability+date.
++++"""
++++val+=+value
++++try:
++++++++val+=+datetime.datetime.strptime(value,+'%25Y-%25m-%25d')
++++except+(ValueError):
++++++++if+value.strip("+-%2B").isdigit():
++++++++++++val+=+int(value)

++++return+val|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|5339892|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>def normalize_availability(value):
 """
 Normalize the availability date.
 """
 val = value
 try:
 val = datetime.datetime.strptime(value, '%Y-%m-%d')
 except (ValueError):
 if value.strip(" -+").isdigit():
 val = int(value)

 return val
</code></pre>

blocks|key|4857584|text|使用方便的帮助器函数。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4857585|def+tryconvert(value,+default,+*types):
++++"""Converts+value+to+one+of+the+given+types.++The+first+type+that+succeeds+is
+++++++used,+so+the+types+should+be+specified+from+most-picky+to+least-picky+(e.g.
+++++++int+before+float).++The+default+is+returned+if+all+types+fail+to+convert
+++++++the+value.++The+types+needn't+actually+be+types+(any+callable+that+takes+a
+++++++single+argument+and+returns+a+value+will+work)."""
++++value+=+value.strip()
++++for+t+in+types:
++++++++try:
++++++++++++return+t(value)
++++++++except+(ValueError,+TypeError):
++++++++++++pass
++++return+default|code-block|syntax|javascript|4857586|然后编写一个解析日期/时间的函数：|4857587|def+parsedatetime(value,+format="%25Y-%25m-%25d")
++++return+datetime.datetime.striptime(value,+format)|4857588|现在把它们放在一起：|4857589|value+=+tryconvert(value,+None,+parsedatetime,+int)|4857590|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|S|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|U|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

Use a handy helper function.

<pre><code>def tryconvert(value, default, *types):
 """Converts value to one of the given types. The first type that succeeds is
 used, so the types should be specified from most-picky to least-picky (e.g.
 int before float). The default is returned if all types fail to convert
 the value. The types needn't actually be types (any callable that takes a
 single argument and returns a value will work)."""
 value = value.strip()
 for t in types:
 try:
 return t(value)
 except (ValueError, TypeError):
 pass
 return default
</code></pre>

Then write a function for parsing the date/time:

<pre><code>def parsedatetime(value, format="%Y-%m-%d")
 return datetime.datetime.striptime(value, format)
</code></pre>

Now put 'em together:

<pre><code>value = tryconvert(value, None, parsedatetime, int)
</code></pre>

I have a variable containing a string (extracted from a XML feed). The string value can be of type integer, date or string. I need to convert it from string to given data type. I am doing it this way but it is a little bit ugly so I am asking if there is a better technique. If I would checking for more types, I will end with very nested try - except blocks.

<pre><code>def normalize_availability(self, value):
 """
 Normalize the availability date.
 """
 try:
 val = int(value)
 except ValueError:
 try:
 val = datetime.datetime.strptime(value, '%Y-%m-%d')
 except (ValueError, TypeError):
 # Here could be another try - except block if more types needed
 val = value
</code></pre>

Thanks!

String checking on multiple types

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我有一个变量，其中包含一个字符串(从XML提要中提取)。字符串值可以是整数、日期或字符串类型。我需要将它从字符串转换为给定的数据类型。我是这样做的，但是有点难看，所以我在问有没有更好的技术。如果我要检查更多的类型，我将以非常嵌套的try - except块结束。def normalize_availability(se...

问对多个类型进行字符串检查
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