Ruby。

Strange scoping rules - variables, constants, and methods each behave differently from each other. The rules change also depending on which keyword you used to create a closure. Or on whether you're in a class, eigenclass, object, module, or module's self. Then there's instance_eval, which changes the rules to a different set of rules. And they change again when a module is "included" or "extended", which themselves do different things to scope. And some sets of rules can't be emulated by metaprogramming, so you have to use eval. Unless you're on ruby 1.9, where all of this is different. Namespacing is basically useless. If you have Foo::File, then the stdlib File is probably broken for all of Foo. require statement is broken. If two files require eachother, the behavior of those files can change dramatically depending on which is loaded first from elsewhere. libraries change APIs dramatically and suddenly, so you have to require specific minor revision numbers of all of your dependencies. For every single ruby application on your system. The rubygems package system overrides "require" rather than putting files in the search path - because why use a system when you can replace it?

Python:

速度 静态分析(缺乏) 匿名函数仅限于一个表达式

C#

Lack of multiple dispatch based on the runtime type of the method arguments. dynamic should solve most of this, but it hasn't been released yet. Interface implementation is declarative not structural. I really like the way Google's Go language is doing types Making asynchronous method calls is really bulky (and I'm pretty sure all threads are OS threads, not lightweight threads) No macro system. I'm not talking about C-style macros here; I'm talking LISP/Scheme style macros Operators are static methods and their signatures are overly constrained (and you can't create new ones).

Python。

虽然前面提到了python处理作用域的奇怪方式，但我觉得最糟糕的结果是:

import random

def myFunction():

    if random.choice(True, False):
        myString = "blah blah blah"

    print myString

也就是说，if块内部的作用域与函数的其余部分相同，这意味着变量声明可以出现在条件分支内部，并且可以在条件分支外部访问。大多数语言要么阻止你这样做，要么至少为你提供某种严格的模式。

此函数有时会成功，但有时会抛出异常。虽然这是一个人为的例子，但这可能会导致一些微妙的问题。

c# / .net:

Classes should be sealed by default There should be no lock statement - instead, you should have specific locking objects, and there should be methods such as Acquire which return disposable lock tokens. Corollary: there shouldn't be a monitor for every object. GetHashCode() and Equals() shouldn't be in System.Object - not everything's suitable for hashing. Instead, have an IdentityComparer which does the same thing, and keep the IComparer<T>, IComparable<T>, IEqualityComparer<T> and IEquatable<T> interfaces for custom comparisons. Poor support for immutability Poor way of discovering extension methods - it should be a much more conscious decision than just the fact that I'm using a namespace.

这些都是我想出来的，明天问我，我会想出一个不同的5个:)

C

字符串操作。

必须手动处理字符串缓冲区是一个容易出错的痛苦。由于如此多的计算实际上是移动和修改字符串(计算机并不像人们想象的那样用于大型数字运算)，因此能够使用托管语言或c++的字符串对象来处理这些非常好。当我必须在直发C时，感觉就像在流沙中游泳。