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

No parametric polymorphism (i.e. C++ templates). It makes writing reusable data structures and algorithms a pain (and there's hardly any static checking). See for instance the comparator argument to qsort and bsearch: the comparator takes void pointers :( No library of data structures. I really hate writing my own hash table. I also really hate scouring the web for a library of reusable data structures. Especially if it turns out to be incomplete. Strings. Inefficient representation, unwieldy if you make it sane, too hard to safely input a string. No standard for snprintf. Too hard to create a format string with sprintf, then use that to create a string with sprintf again, in a safe way. Only lexical macros. If different compilers expects function annotation in different places, I have to put the same HAS_NO_SIDE_EFFECTS in different places. Why can't I just grab the function, switch over the compiler type, and then insert it at the right place by a macro call? No portable libraries for common functionality. For sockets and threading, I use SDL---a frigging game library. For .ini-style parsers, the only library I could find which was packaged for ubuntu, I posted on the daily wtf (it calculates an array of hash values, then does a linear scan through it...)

C++

Template syntax is heavy and unweildy. Let's see, for(map<string, int>::const_iterator it = mymap.begin(); it != mymap.end(); ++it). Design errors in the STL. Should changing allocation strategy for your vector really change its type? Overly complex type system. Type T1 has a convert-to-T2 method, and T2 has an implicit from-T1 constructor. Which is called? How does overloading, overriding and multiple inheritance interact? Poorly, I guess... Incredibly long and unwieldy error messages from templates. You know what I mean... References means you can't see output parameters at call sites. In C, you can guess what foo(bar, &baz) can and can't modify.

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:)

我是在冒险，因为我不能全职使用它，但无论如何我会尝试一下!

Perl 6

func("frew") != func ("frew") It annoys me, but there is good reason for it. In Perl 5 print (5 + 6) * 10 still gets me every now and then It may be easier to parse than Perl 5 in a lot of places, but it still kills my editor sometimes It still has a lot of the line noise Perl 5 which scares a lot of people. That means it's harder to get them excited etc. There are no libraries yet. This will be a non issue if Perl 6 does indeed end up supporting Perl 5, but that may be a burden not worth bearing. There's no REPL, or what rubyists would call irb. A solid interactive Perl 6 with tab completion, color coding, etc, would make using and learning it so much nicer. Currently the documentation is basically the English spec. Not exactly an easy read. I know it's a stupid cliche, but it's not out yet! (I am allowed to complain because I am helping :-P)

前三点是语言;剩下的并不是语言本身，而是它还没有问世的事实。

JavaScript:

The Object prototype can be modified. Every single object in your program gets new properties, and something probably breaks. All objects are hash maps, but it's difficult to safely use them as such. In particular, if one of your keys happens to be __proto__, you're in trouble. No object closure at function reference time. In fact, no object closure at all -- instead, this is set whenever a function is called with object notation or the new operator. Results in much confusion, particularly when creating event callbacks, because this isn't set to what the programmer expects. Corollary: calling a function without object notation or the new operator results in this being set equal to the global object, resulting in much breakage. Addition operator overloaded to also perform string concatenation, despite the two operations being fundamentally different. Results in pain when a value you expect to be a number is in fact a string. == and != operators perform type coercion. Comparisons between different types involve a list of rules that no mortal can remember in full. This is mitigated by the existence of === and !== operators. Both null and undefined exist, with subtly different, yet redundant meanings. Why? Weird syntax for setting up prototype chains. parseInt(s) expects a C-style number, so treats values with leading zeroes as octal, etc. You can at least parseInt(s, 10) but the default behaviour is confusing. No block scope. Can declare the same variable more than once. Can use a variable without declaring it, in which case it's global and probably breaks your program. with { }. Really difficult to document with JavaDoc like tools.

c#中缺少预处理器。

我知道他们把它放在一边是因为有些人会滥用它，但我认为他们把孩子和洗澡水一起倒掉了。代码生成被认为是一件好事，在c++中，预处理程序是我的第一个代码生成器。