🌐 Mailman 3 May 2020 - Python-list - python.org

Re: Behaviour of os.path.join
by BlindAnagram May 26, 2020

May 26, 2020

On 26/05/2020 17:46, MRAB wrote: > On 2020-05-26 16:48, BlindAnagram wrote: >> On 26/05/2020 16:22, Ben Bacarisse wrote: >>> BlindAnagram <blindanagram(a)nowhere.com> writes: >>> >>>> I came across an issue that I am wondering whether I should report >>>> as an >>>> issue. If I have a directory, say: >>>> >>>> base='C:\\Documents' >>>> >>>> and I use os.path.join() as follows: >>>> >>>> join(base, '..\\..\\', 'build', '') >>> >>> It rather defeats the purpose of os.sep if you include it in a part of >>> the path. What you mean is better expressed as >>> >>> join(base, '..', '..', 'build', '') >>> >>> (and base includes it too, but I can't suggest an alternative because I >>> don't know your intent is far as defaults go.) >> >> Thanks for your input but while that part of my path may not be to your >> liking, it works fine and does not seem to be relevant to my concern, >> which is that join appears to treat os.sep as an absolute path, which it >> is not. >> > If it starts with the path separator, then it's absolute (well, absolute > on that drive). Agreed. I did not think that I needed to add this exception to my comment as I thought from the the context that it would be clear that I was questioning how it worked at the end of a path, not when used at its start.

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Re: Behaviour of os.path.join
by BlindAnagram May 26, 2020

May 26, 2020

On 26/05/2020 16:25, Stefan Ram wrote: > BlindAnagram <blindanagram(a)nowhere.com> writes: >> The documentation says that an absolute path in the parameter list for >> join will discard all previous parameters but '\\' is not an absoute path! > > The source code for "join" in "ntpath.py" does not seem to > bother to call "is_absolute". Instead it contains (simplified): > > seps = '\\/' > if p_path and p_path[0] in seps: > # Second path is absolute Thanks, that seems to confirm this as a bug.

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Custom logging function
by zljubisic＠gmail.com May 26, 2020

May 26, 2020

Hi, I have a case in which I have to use custom function for logging. For example, all messages should go to stderr and end with '\r\n'. Can I somehow use standard python logging module but send all message to stderr with '\r\n' line endings? Regards

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Decorators with arguments?
by Christopher de Vidal May 25, 2020

May 25, 2020

Help please? Creating an MQTT-to-Firestore bridge and I know a decorator would help but I'm stumped how to create one. I've used decorators before but not with arguments. The Firestore collection.on_snapshot() method invokes a callback and sends it three parameters (collection_snapshot, changes, and read_time). I need the callback to also know the name of the collection so that I can publish to the equivalent MQTT topic name. I had thought to add a fourth parameter and I believe a decorator is the right approach but am stumped how to add that fourth parameter. How would I do this with the code below? #!/usr/bin/env python3 from google.cloud import firestore import firebase_admin from firebase_admin import credentials import json import mqtt firebase_admin.initialize_app(credentials.Certificate("certs/firebase.json")) db = firestore.Client() mqtt.connect() def load_json(contents): try: return json.loads(contents) except (json.decoder.JSONDecodeError, TypeError): return contents def on_snapshot(col_name, col_snapshot, changes, read_time): data = dict() for doc in col_snapshot: serial = doc.id contents = load_json(doc.to_dict()['value']) data[serial] = contents for change in changes: serial = change.document.id mqtt_topic = col_name + '/' + serial contents = data[serial] if change.type.name in ['ADDED', 'MODIFIED']: mqtt.publish(mqtt_topic, contents) elif change.type.name == 'REMOVED': mqtt.publish(mqtt_topic, None) # Start repeated code section # TODO Better to use decorators but I was stumped on how to pass arguments def door_status_on_snapshot(col_snapshot, changes, read_time): on_snapshot('door_status', col_snapshot, changes, read_time) door_status_col_ref = db.collection('door_status') door_status_col_watch = door_status_col_ref.on_snapshot(door_status_on_snapshot) # Repetition... def cpu_temp_on_snapshot(col_snapshot, changes, read_time): on_snapshot('cpu_temp', col_snapshot, changes, read_time) cpu_temp_col_ref = db.collection('cpu_temp') cpu_temp_col_watch = cpu_temp_col_ref.on_snapshot(cpu_temp_on_snapshot) # End repeated code section # Start repeated code section door_status_col_watch.unsubscribe() cpu_temp_col_watch.unsubscribe() # Repetition... # End repeated code section Christopher de Vidal Would you consider yourself a good person? Have you ever taken the 'Good Person' test? It's a fascinating five minute quiz. Google it.

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Re: Writing output of function to a csv file
by Ciarán Hudson May 25, 2020

May 25, 2020

Thanks, between this message and the one below I was able to understand my error and fix it. I really appreciate the help.

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Re: Writing output of function to a csv file
by Manfred Lotz May 25, 2020

May 25, 2020

On Mon, 25 May 2020 19:25:08 +0100 MRAB <python(a)mrabarnett.plus.com> wrote: > On 2020-05-25 19:00, Ciarán Hudson wrote: > > Hi, > > > > In the code below, which is an exercise I'm doing in class > > inheritance, almost everything is working except outputting my > > results, which as the function stock_count, to a csv. stock_count > > is working in the code. And I'm able to open and close the csv > > called cars, but the stock_count output is not being written to the > > file. Any suggestions? > [snip] > > > > def stock_count(self): > > print('petrol cars in stock ' + str(len(self.petrol_cars))) > > print('electric cars in stock ' + > > str(len(self.electric_cars))) print('diesel cars in stock ' + > > str(len(self.diesel_cars))) print('hybrid cars in stock ' + > > str(len(self.hybrid_cars))) > > > > def process_rental(self): > > answer = input('would you like to rent a car? y/n') > > if answer == 'y': > > self.stock_count() > > answer = input('what type would you like? p/e/d/h') > > amount = int(input('how many would you like?')) > > if answer == 'p': > > self.rent(self.petrol_cars, amount) > > if answer == 'd': > > self.rent(self.diesel_cars, amount) > > if answer == 'h': > > self.rent(self.hybrid_cars, amount) > > else: > > self.rent(self.electric_cars, amount) > > self.stock_count() > > > > file = open("cars.csv","w") > > file.write(str(self.stock_count())) > > file.close() > > > In 'stock_count' you're telling it to print to the screen. Nowhere in > that function are you telling it to write to a file. I think something gets written to 'cars.csv', namely the string 'None'. -- Manfred

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Writing output of function to a csv file
by Ciarán Hudson May 25, 2020

May 25, 2020

Hi, In the code below, which is an exercise I'm doing in class inheritance, almost everything is working except outputting my results, which as the function stock_count, to a csv. stock_count is working in the code. And I'm able to open and close the csv called cars, but the stock_count output is not being written to the file. Any suggestions? There are 2 python files as the exercise is about class inheritance. I'll paste the code from both. cars.py # Define a class for my car class Car(object): # implement the car object. def __init__(self): self.__colour = '' self.__make = '' self.__mileage = 0 self.engineSize = '' def getColour(self): return self.__colour def getMake(self): return self.__make def getMileage(self): return self.__mileage def setColour(self, colour): self.__colour = colour def setMake(self, make): self.__make = make def setMileage(self, mileage): self.__mileage = mileage def paint(self, colour): self.__colour = colour return self.__colour def move(self, distance): self.__mileage = self.__mileage + distance return self.__mileage class ElectricCar(Car): def __init__(self): self.__numberFuelCells = 1 def getNumberFuelCells(self): return self.__numberFuelCells def setNumberFuelCells(self, value): self.__numberFuelCells class PetrolCar(Car): def __init__(self): self.__choke = 0 def __getChoke(self): return self.__choke def __setChoke(self, value): self.__choke = value class DieselCar(Car): def __init__(self): self.__dpf = 0 def __getDpf(self): return self.__dpf def __setDpf(self, value): self.__dpf = value class HybridCar(Car): def __init__(self): self.__regeneration = 0 def __getRegeneration(self): return self.__regeneration def __setRegeneration(self, value): self.__regeneration = value dealership.py import csv from car import Car, ElectricCar, PetrolCar, DieselCar, HybridCar class Dealership(object): def __init__(self): self.electric_cars = [] self.petrol_cars = [] self.diesel_cars = [] self.hybrid_cars = [] def create_current_stock(self): for i in range(6): self.electric_cars.append(ElectricCar()) for i in range(20): self.petrol_cars.append(PetrolCar()) for i in range(10): self.diesel_cars.append(DieselCar()) for i in range(4): self.hybrid_cars.append(HybridCar()) def stock_count(self): print('petrol cars in stock ' + str(len(self.petrol_cars))) print('electric cars in stock ' + str(len(self.electric_cars))) print('diesel cars in stock ' + str(len(self.diesel_cars))) print('hybrid cars in stock ' + str(len(self.hybrid_cars))) def rent(self, car_list, amount): if len(car_list) < amount: print('Not enough cars in stock') return total = 0 while total < amount: car_list.pop() total = total + 1 def process_rental(self): answer = input('would you like to rent a car? y/n') if answer == 'y': self.stock_count() answer = input('what type would you like? p/e/d/h') amount = int(input('how many would you like?')) if answer == 'p': self.rent(self.petrol_cars, amount) if answer == 'd': self.rent(self.diesel_cars, amount) if answer == 'h': self.rent(self.hybrid_cars, amount) else: self.rent(self.electric_cars, amount) self.stock_count() file = open("cars.csv","w") file.write(str(self.stock_count())) file.close() dealership = Dealership() dealership.create_current_stock() proceed = 'y' while proceed == 'y': dealership.process_rental() proceed = input('continue? y/n')

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stderr writting before stdout
by Souvik Dutta May 25, 2020

May 25, 2020

Hi, Is there any precedence or priority order by which sys.stderr.write() and sys.stdout.write() works. Because when running the below code... import sys sys.stdout.write("Writting") sys.stderr.write("No errors \n") No errors is written (displayed) first and writting is written later. Why does this happen?

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Strings: double versus single quotes
by Manfred Lotz May 24, 2020

May 24, 2020

Hi there, I am asking myself if I should preferably use single or double quotes for strings? If I need a single quote in a string I would use double quotes for the whole string and vice versa. For f-strings I mostly see double quotes but single quotes would work as well I think. Is there a recommendation? -- Manfred

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Re: Strings: double versus single quotes
by Manfred Lotz May 24, 2020

May 24, 2020

On Sat, 23 May 2020 14:46:04 -0400 Dennis Lee Bieber <wlfraed(a)ix.netcom.com> wrote: > On Sat, 23 May 2020 11:03:09 -0500, Tim Chase > <python.list(a)tim.thechases.com> declaimed the following: > > > > > >But when a string contains both, it biases towards single quotes: > > > > >>> "You said \"No it doesn't\"" > > 'You said "No it doesn\'t"' > > This is where using triple quotes (or triple apostrophes) > around the entire thing simplifies it all... (except for a need to > separate the four ending quotes) Exactly, I also would opt for triple quotes in this case. > > >>> """You said "No it doesn't" """ > 'You said "No it doesn\'t" ' > >>> '''You said "No it doesn't"''' > 'You said "No it doesn\'t"' > >>> > > NO \ escapes needed on the input strings. > > >>> print("""You said "No it doesn't" """) > You said "No it doesn't" > >>> print('''You said "No it doesn't"''') > You said "No it doesn't" > >>> > > -- Manfred

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