Python Newbie
Hi folks. I am a long time C sharp dev, just learning Python now due to job requirements. My initial impression is that Python has got to be the most ambiguous and vague language I have seen to date. I have major issues with the fact that white space matters. How do you deal with this? For example, you open a source file in different editors and the indentation levels change even though i only have spaces, no tabs (compare Windows Notepad and Notepad++). Which editor do you trust? In addition, code is difficult to read because you cannot lay it out in easily discernable blocks. For example, I always tend to indent a full 'if' statement block so that it is easier to see where the if block starts and ends. Can't do that in Python. What is even more frustrating is that Python is inconsistent with its syntax. For example, when I write "if (myVariable != 0):" then this is OK but "for (i in intAry):" results in syntax error. Apparently Python has problems with my use of parentheses. How retarded. I think I will rather find another job than eat my nerves with Python. Any comments on this before I quit my job? -- http://mail.python.org/mailman/listinfo/python-list
Re: Python Newbie
"Jean-Michel Pichavant" wrote in message news:mailman.2567.1361905815.2939.python-l...@python.org... - Original Message - Hi guys, Question. Have this code intX = 32 # decl + init int var intX_asString = None # decl + init with NULL string var intX_asString = intX.__str__ ()# convert int to string What are these ugly underscores for? _str___ Peter -- http://mail.python.org/mailman/listinfo/python-list I can't wait for the intX_asString_asBool = intX_asString.__bool__() if (intX_asString_asBool == True): # do something ;-) JM As serious a character as I am, I had good laughs at this. Don't you all like my questions for all the exitainment they offer? The "__str__" issue was a genuine question. I'm glad to find there is also a __bool_ () method, shall I need it. :-) Please note, this is not how I write my code. I'm not that bad a programmer, it's just Python which is so different that I am doing what I need to help clarify things and help me out. I don't find this post offensive, even though JM is deliberately making fun of me. But to his credit, it is funny indeed. Let's laugh 2gether! This reminds me, when I first started working with databases and saw an error msg which said that my query had "ambiguous columns" I laughed for 1/2 hr. I found it incredibly exitaining that a 100% deterministic piece of hardware could have the word "ambiguous" in its internal dictionary. :-)) Peter -- http://mail.python.org/mailman/listinfo/python-list
Re: Python Newbie
Thanks to all for quick relies.
Chris, you are (almost) spot on with the if blocks indentation. This is what I
do, and it has served me well for 15 years.
code
code
if (some condition)
{
code
code
}
code
code
This is what I call code clarity. With Python, I am having to do this
code
code
##
if (some condition):
code
code
##
code
code
It does the job, but is not ideal.
I am nervous about using variables "out of the blue", without having to declare
them. For example, when I write "i = 0" it is perfectly OK to Python without
'i' being declared earlier. How do I know that I haven't used this variable
earlier and I am unintentionally overwriting the value? I find I constantly
have to use the search facility in the editor, which is not fun.
You see, Javascript, for one, behaves the same way as Python (no variable
declaration) but JS has curly braces and you know the variable you have just
used is limited in scope to the code within the { }. With Python, you have to
search the whole file.
Thanks to Chris, Ian and Dave for explaining the () issue around if and for
statement. I don't agree with this, but I understand your points. The reason
why I like parentheses is because they help with code clarity. I am obsessed
with this. :-) After all, there is a reason why so many languages have required
them for several decades.
What about Python's ambiguity?
For example, in C you would write
if (myVar != 0)
do something
in Python, this is legal
if (not myVar):
do something
What does this mean? Is it a test for myVar being equal to zero or a test for
null, or else?
I want to learn a new language but Python's quirks are a bit of a shock to me
at this point. I have been Pythoning only for about a week.
In the mean time, thanks to most of you for encouraging me to give Python a
chance. I will do my best to like it, w/o prejudice.
Peter
--
http://mail.python.org/mailman/listinfo/python-list
Re: Python Newbie
Hi Chris, Thanks for this. Regarding ambiguity, you will never find me write ambiguous code. I don't sabotage my own work. But the reality is that in addition to writing my own code, I have to maintain existing. I find it incredibly confusing then I see a statement along the lines of "if not something" - have to study the code in detail to see what it is testing. I could show more examples of what I find confusing in existing code, but I don't intent to troll. I'm just trying to understand the language as it is. I will see how it goes. Pete -- http://mail.python.org/mailman/listinfo/python-list
Re: Python Newbie
Thanks to everyone for all the posts, some friendly some not. I read all of them with genuine interest. So I am continuing to learn Python, here are my new observations for your consideration. There seems to be a "heated" argument about Python's apparently intentional ambiguity in conditional statements. Specifically, the issue is, is it more appropriate to write (as an example) if (some statement):# short form rather than if (some statement == true):# long form Some 50(?) years ago, C was designed so that everything other than 0 evaluated to true and was false otherwise. Fast forward to recent memory, when C# was designed, Microsoft claims they reviewed all the features of C, C++ and Java, pulled the best features from each of these languages and designed a new language that would help minimize the potential for planting bugs. Say what you want about MS inventions, but my experience is that to require the long form notation was a good decision. For me the fact that the short notation is legal in Python is a stepback in language design. Python inventors, when creating what is after all considered a contemporary language, should have known better. Call me psychopath if you will (have seen this in one post), but I shall continue to use the aforementioned long form as I always have, and no Python is going to change that. Today I learned the hard way that all function parameters in Python are passed by reference (meaning whatever happens to them inside a function, new values are always passed to caller). Not good. I got caught up on this. To combat the mostly unwanted behavior, inside a function I have to reassign variables intended to be local to new variables. A pain. Can anyone offer ONE reason why Python was designed that way? Out of curiosity, does anyone have any idea why function declarations are preceded by the keyword "def" rather than something more intuitive like "function" or at least "func", perhaps? Does anyone know what the benefit of writing the cryptic "elif" to mean "else if" is? Curiously, the default statement in an if/else chain is preceded by "else" and not "el". Someone said I am too narrow-sited appreciating C# and not open to alternate approaches to language design. Well if that someone says "def" is better than "function" and "elif" is better than "else if", then dare I say, you are obsessed with Python! So far I am getting the impression that Python is a toy language of some kind (similar to Basic of the early 80's), not really suitable for serious work. The only difference between these languages (admittedly, a serious one) is the existence of extensive libraries. Otherwise there would be no good reason for Python to exist. Nevertheless, it does exist and I have to learn it. As long as someone is paying for my time, that's OK with me. Peter -- http://mail.python.org/mailman/listinfo/python-list
Re: Python Newbie
Hi Ian, Thanks for typing all this for me. Really useful. I did some googling of my own and I found that there was no concept of boolean in older versions of Python like you said. (BTW, how does this omission go well with proper language design, as Oscar seems to have hinted?) I think this obvious shortcomming is the main reason that, for example, when x holds the value of 5, x is considered to be "true". You see, I have to maintain Python files (ubuntu server scripts) which are 2000 lines long, all sequential code, no functions. While the person who wrote them should be shot :), the fact that there is inherent ambiguity with value, none, null 0, you name it, in conditional statements is not helping me understand the code, and this adds to my frustration. I messed up my if (some statement):# short form in the example I gave, but you figured exactly what I mean. Of course if the condition (some statement) is boolean there is no point adding "== true" or similar. But if (some statement) represents a value this is where I have trouble and again the origins of this date back to when Python had no boolean type. So now at least I understand it. Btw, there are still languages with no boolean type today, MySQL for one. This creates big efficiency problems when fetching data from the database into a C# program - what should be a bool is fetched as an 8-byte integer! But that's a different story. I shut up now. As I said I am new to Python, learning it, I have to get more experience with passing parameter values to functions, as I do with mostly everything else. Cheers. Peter -- http://mail.python.org/mailman/listinfo/python-list
Re: Python Newbie
Hi all, (Ethan, I like your "resident troll" statement. Highly exit-aining!) Thanks for all the input. I did not expect to get so much constructive feedback, the more so that my initial attitude towards Python has been less than positive, diplomatically speaking. Yes, it's true that I am trying to write C# code in Python. It is not going to change any time soon, if at all - I have done too much C#ing, C++ing before that and C-ing earlier still. What surprises me a bit is that no one has said one word against C#, as a form of retaliation against me not being in love with Python. And C# does have its share of concerns, like any language. So far I like the community a lot better than Python. I am trying to learn some Python on my own (besides faffing with it on the job, to use a britishizm). I have discovered today there is no do...while type loop. [Sigh] Peter -- http://mail.python.org/mailman/listinfo/python-list
Re: Python Newbie
Hi guys, Question. Have this code intX = 32 # decl + init int var intX_asString = None # decl + init with NULL string var intX_asString = intX.__str__ ()# convert int to string What are these ugly underscores for? _str___ Peter -- http://mail.python.org/mailman/listinfo/python-list
Re: Python Newbie
> To demonstrate that the person who wrote this code was not a good Python > > programmer. I hope it wasn't you :-) This person obviously had a very > > basic, and confused, understanding of Python. > > > > And, quite frankly, was probably not a very good programmer of *any* > > language: > > > > - poor use of Hungarian notation for variable names; > > - pointless pre-declaration of values; > > - redundant comments that don't explain anything. > > > > If that code came from the code-base you are maintaining, no wonder you > > don't think much of Python! That looks like something I would expect to > > see at the DailyWTF. Hi. Steve, I don't know where you have been over the past couple of days but it is widely known (if the thread title is any indication) that I am indeed very new to Python, but not new to programming in general. To give a bit of background where I found __str__, I am using a Python IDE called PyScripter. Its Intellisense is full of methods starting and ending with "__", hence the question. Regarding Hungarian notation, I don't use it in any other language but Python and JS. Call it poor, but it helps me to remember what type a variable is. The redundant comments serve the same purpose. As for "pointless predeclaration", it helps me know where in the code I first started using the variable, so I know there are no references to it before then. Peter -- http://mail.python.org/mailman/listinfo/python-list
Re: Python Newbie
> > if (some statement):# short form > > > > rather than > > > > if (some statement == true):# long form > > > What all those ugly brackets are for? > Mark, Back in the day when C was king, or take many newer long established languages (C#, Java), the use of () has been widespread and mandated by the compilers. I have never heard anyone moan about the requirement to use parentheses. Now come Python in which parens are optional, and all of a sudden they are considered bad and apparently widely abandoned. Do you really not see that code with parens is much more pleasing visually? I could understand someone's reluctance to use parens if they are very new to programming and Pythons is their first language. But my impression here is that most group contributors are long-time programmers and have long used () where they are required. Again, I'm really surprised the community as a whole ignores the programming "heritage" and dumps the parens in a heartbeat. Peter -- http://mail.python.org/mailman/listinfo/python-list
Re: Python Newbie
Josh, Not thank you for your malicious post. I think you are missing the point here. My source code was just a dummy to offer context for the question I wanted to ask. Further down the line, if I ever feel I don't need to pseudo-declare variables I will stop doing it. But for the moment I am trying to imitate familiar ground. My code as written has no syntax errors, so what's the problem? It is highly unlikely you will ever read any of my Python code - no need to get excited over a few of my lines. And you don't need to answer questions which were not posed, thank you. I wanted Python to register what type of variable I'm after. So I init my vars accordingly, int might be 0, float 0.0 and string with null, err... None. In practice, I wouldn't define an intX_asString var, I would do "str (num)" every time a string representation is needed, provided it isn't a loop, as in that context the expression would probably negatively impact performance in an interpreted language. Peter -- http://mail.python.org/mailman/listinfo/python-list
Re: Python Newbie
>> intX = 32 # decl + init int var > How is it not obvious that "intX" is an integer *without* the comment? Indeed the assignment is enough to deduce "intX" is an int. The comment is there to let me know it is unlikely intX appears earlier in the code. Please, let me do things my way until I find reasons to the contrary. Regarding my use of None to mean NULL, point taken to use "" instead. Peter -- http://mail.python.org/mailman/listinfo/python-list
Re: Python Newbie
> For example (I believe it's already been mentioned) "declaring" intX with > some integer value does *nothing* to maintain > > X as an integer: > > --> intX = 32 > > --> intX = intX / 3.0 > > --> intX > > 10.66 > Yes I did see that it is possible to redefine the type of a variable. But I don't think I would ever do this intentionally; need to be really careful with Python. Peter -- http://mail.python.org/mailman/listinfo/python-list
