小编k99*_*k99的帖子

我在CentOS 5.4上安装了Python 2.6.6,

[@SC-055 lxml-2.3beta1]$ python
Python 2.6.6 (r266:84292, Jan  4 2011, 09:49:55) 
[GCC 4.1.2 20080704 (Red Hat 4.1.2-46)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> 

我想使用lxml模块,但是从源代码构建失败:

src/lxml/lxml.etree.c:157929: error: ‘xsltLibxsltVersion’ undeclared (first use in this function)
src/lxml/lxml.etree.c:157941: error: ‘__pyx_v_4lxml_5etree_XSLT_DOC_DEFAULT_LOADER’ undeclared (first use in this function)
src/lxml/lxml.etree.c:157941: error: ‘xsltDocDefaultLoader’ undeclared (first use in this function)
src/lxml/lxml.etree.c:157950: error: ‘__pyx_f_4lxml_5etree__xslt_doc_loader’ undeclared (first use in this function)
error: command 'gcc' failed with exit status 1

如何在category_id删除类别时自动将产品设置为默认值？例如1,指向第一个类别.

class Product(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(80))
    content = db.Column(db.Text(), unique=True)
    category_id = db.Column(db.Integer, db.ForeignKey('category.id'))
    atime = db.Column(db.DateTime())

    def __init__(self, name, content, category_id):
        self.name = name
        self.content = content
        self.category_id = category_id
        self.atime = datetime.now()

    def __repr__(self):
        return '<Product %r>' % self.id

class Category(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(80))
    products = db.relationship('Product', backref='category', cascade="all, delete, delete-orphan")

    def __init__(self, *args, **kwargs):
        if len(kwargs) > 0:
            self.name = kwargs['name']

    def __repr__(self):
        return '<Category …

如何在pywebkit中为file://协议启用xmlhttprequest？

就像铬一样

http://www.google.com/support/forum/p/Chrome/thread?tid=171316324d16747b&hl=en

我看到了以下代码：

char *str;
// Some code
if (! str || ! *str)
    return str;

为什么需要检查! *str？还if (! str)不够吗