4 ms·

> the vision of the Python ecosystem as Python-only packages with occasional lightweight C libraries integrated with cffi looks very nice to me. I have the opp

> the vision of the Python ecosystem as Python-only packages with occasional lightweight C libraries integrated with cffi looks very nice to me. I have the opposite view. I'd rather have all of the important libraries written in a language with a safer type system than Python's. C's type system has some safety issues, but it's still safer than Python's. If Python 3's optional type hints could actually be enforced at runtime, I'd be sold on using Python for pretty much everything.

rer 10y ago
How is Python's type system less safe than C's?
nnq 10y ago
> C's type system has some safety issues, but it's still safer than Python's. Uhm. An error in Python code code can lead to a runtime crash with an exception or a bad result ...most of the time. An error in C can lead to anything from an impossibly hard to diagnose memory leak to an exploitable buffer overflow... most of the time. C may be be "statically typed", but I think the number of people capable of writing (and maintaining!) secure C code is incredibly low. Heck, even the openssl devs failed at this at least once. And the fact that C is "static" and Python is "dynamic" does not make C's type system safe. Heck, even js's type "system" is safer than C's if when you use the word safe you refer to, you know, security.
wolf550e 10y ago
A language with undefined behavior is not suitable for new code in 2016 if you have alternatives.
- twblalock 10y ago
  Python has undefined behavior because it's implementations are written in languages that do. Every implementation of it is written in a language with undefined behavior such as C, or in languages which are themselves implemented in languages with undefined behavior (e.g. Jython, which runs on the JVM, which is written in C and C++). There is no guarantee that an implementation of Python is bug-free, so there is no guarantee that any Python problem is free of undefined behavior. So, if you write a Python library in C or in Python, you'll have undefined behavior either way. Undefined behavior is not a good criteria for choosing which language to use.
  - dalke 10y ago
    I think you have mixed multiple definitions of "undefined behavior". A language can say that certain operations are undefined, like reference NULL in C. What of the Python language is undefined? (Some things, like garbage collection, are implementation defined. That is different.) Even if a language contains undefined behavior, a program written in that language can avoid the undefined operations. What of the Python implementations use or depend on undefined operations in the lower-level language? An implementation can also be flawed. But that's not "undefined behavior" but non-conformant behavior. "A bug", in the vernacular. According to your definition, is there any language that doesn't have undefined behavior? After all, even the hardware can have flaws and undefined behavior, so to mix metaphors, it's all a house of cards built upon sand.
    - twblalock 10y ago
      > According to your definition, is there any language that doesn't have undefined behavior? After all, even the hardware can have flaws and undefined behavior, so to mix metaphors, it's all a house of cards built upon sand. That's correct, and it's not pedantic to point that out. It proves that undefined behavior is not a useful criteria for choosing which language to use. But even if we accept your more restricted definition of what constitutes undefined behavior, we still must accept that any language that is implemented in C could possibly exhibit any of C's undefined behavior. Therefore, writing a Python library in Python instead of C cannot help you avoid C's undefined behavior. It might prevent you from introducing more undefined behavior, but that's not the same as avoiding it entirely -- if the implementation is written in C, then that ship has sailed.
      - dalke 10y ago
        I now realize I did not understand your original comment. Thank you for the clarification. I don't agree with how you use "undefined behavior", but it's appropriate for the OP's context.
        twblalock 10y ago

rer 10y ago

How is Python's type system less safe than C's?

nnq 10y ago

> C's type system has some safety issues, but it's still safer than Python's. Uhm. An error in Python code code can lead to a runtime crash with an exception or a bad result ...most of the time. An error in C can lead to anything from an impossibly hard to diagnose memory leak to an exploitable buffer overflow... most of the time. C may be be "statically typed", but I think the number of people capable of writing (and maintaining!) secure C code is incredibly low. Heck, even the openssl devs failed at this at least once. And the fact that C is "static" and Python is "dynamic" does not make C's type system safe. Heck, even js's type "system" is safer than C's if when you use the word safe you refer to, you know, security.

wolf550e 10y ago

A language with undefined behavior is not suitable for new code in 2016 if you have alternatives.

twblalock 10y ago
Python has undefined behavior because it's implementations are written in languages that do. Every implementation of it is written in a language with undefined behavior such as C, or in languages which are themselves implemented in languages with undefined behavior (e.g. Jython, which runs on the JVM, which is written in C and C++). There is no guarantee that an implementation of Python is bug-free, so there is no guarantee that any Python problem is free of undefined behavior. So, if you write a Python library in C or in Python, you'll have undefined behavior either way. Undefined behavior is not a good criteria for choosing which language to use.
- dalke 10y ago
  I think you have mixed multiple definitions of "undefined behavior". A language can say that certain operations are undefined, like reference NULL in C. What of the Python language is undefined? (Some things, like garbage collection, are implementation defined. That is different.) Even if a language contains undefined behavior, a program written in that language can avoid the undefined operations. What of the Python implementations use or depend on undefined operations in the lower-level language? An implementation can also be flawed. But that's not "undefined behavior" but non-conformant behavior. "A bug", in the vernacular. According to your definition, is there any language that doesn't have undefined behavior? After all, even the hardware can have flaws and undefined behavior, so to mix metaphors, it's all a house of cards built upon sand.
  - twblalock 10y ago
    > According to your definition, is there any language that doesn't have undefined behavior? After all, even the hardware can have flaws and undefined behavior, so to mix metaphors, it's all a house of cards built upon sand. That's correct, and it's not pedantic to point that out. It proves that undefined behavior is not a useful criteria for choosing which language to use. But even if we accept your more restricted definition of what constitutes undefined behavior, we still must accept that any language that is implemented in C could possibly exhibit any of C's undefined behavior. Therefore, writing a Python library in Python instead of C cannot help you avoid C's undefined behavior. It might prevent you from introducing more undefined behavior, but that's not the same as avoiding it entirely -- if the implementation is written in C, then that ship has sailed.
    - dalke 10y ago
      I now realize I did not understand your original comment. Thank you for the clarification. I don't agree with how you use "undefined behavior", but it's appropriate for the OP's context.
      - twblalock 10y ago