如何修复“拒绝执行'常量'语句".错误? [英] How to fix "execution of 'Constant' statements is denied" error?

问题描述

我正在遵循web.py文档中的模板指南

I'm following the tutorial in web.py documentation for templates

    import web
    render = web.template.render('templates')
    print (render.hello('world'))

但是，当运行python文件时，会导致错误:'Constant'语句的执行被拒绝".Google搜索没有找到任何答案，请给我一些帮助.谢谢

However when running the python file results in an error :"execution of 'Constant' statements is denied". Google searching doesn't turn up any answers,I need some help please. Thank You

推荐答案

web.py不允许在模板中执行某些类型的python法律声明.我不知道为什么它不允许您的特定声明，但是有一种方法可以让模板做更多的事情:

web.py disallows some types of python legal statements to be executed within the template. I don't know why it's disallowing your particular statement, but there's a way to allow templates to do more:

web/template.py包含列表 ALLOWED_AST_NODES ，它们是模板中允许的结构(由抽象语法树解析器使用).您可以更改它.

web/template.py contains a list ALLOWED_AST_NODES which are constructs (used by the abstract syntax tree parser) which are permitted in within templates. You can change that.

在您的代码中，添加一次:

In your code, add once:

from web.template import ALLOWED_AST_NODES
ALLOWED_AST_NODES.append('Constant')

现在，这不是必须的，因此我怀疑您的代码中还有其他问题…….可能是多种版本?我相信常数"是python3 AST中的一个节点，而不是python2中的一个节点吗?

Now, this shouldn't be necessary, so I suspect there's something else going on in your code.... mix of versions, perhaps? I believe 'Constant' is a node in python3 AST, but not in python2?

这是将字典理解 .append('DictComp')添加到允许的模板ast节点的有用技术，因为它已经允许列表理解.

This is a useful technique to add dictionary comprehension .append('DictComp') to the template allowed ast nodes as it already permits list comprehension.

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