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Jeroen W. Pluimers on .NET, C#, Delphi, databases, and personal interests

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Archive for January 8th, 2020

Python – list transformation; string formatting – Stack Overflow

Posted by jpluimers on 2020/01/08

Sometimes simple examples are the best: [WayBack] Python – list transformation – Stack Overflow.

Interactive example (note you can run and save at repl.it in either [WayBack] Repl.it – Python 3 or [WayBack] Repl.it – Python 2; you can run but not save it at [WayBack] Welcome to Python.org: interactive Python shell):

# Links the documentation are Python 2, though everything works in Python 3 as well.

x = [1,2,3,4,5,11]
print("x: ", repr(x))

y = ['01','02','03','04','05','11']
print("y: ", repr(y))

# List comprehension https://docs.python.org/2/tutorial/datastructures.html#list-comprehensions
# ... using `str.format()` (Python >= 2.6): https://docs.python.org/2/library/stdtypes.html#str.format and https://docs.python.org/2/library/string.html#formatstrings
y = ["{0:0>2}".format(v) for v in x]
print("y: ", repr(y))

# ... using the traditional `%` formatting operator (Python < 2.6): https://docs.python.org/2/library/stdtypes.html#string-formatting y = ["%02d" % v for v in x] print("y: ", repr(y)) # ... using the format()` function (Python >= 2.6): https://docs.python.org/2/library/functions.html#format and https://docs.python.org/2/library/string.html#formatstrings
# this omits the "{0:...}" ceremony from the positional #0 parameter
y = [format(v, "0>2") for v in x]
print("y: ", repr(y))

# Note that for new style format strings, the positional argument (to specify argument #0) is optional (Python >= 2.7) https://docs.python.org/2/library/string.html#formatstrings
y = ["{:0>2}".format(v) for v in x]
print("y: ", repr(y))

# Using `lambda`
# ... Python < 3 return a list y = map(lambda v: "%02d" %v, x) print("y: ", repr(y)) # ... Python >= 3 return a map object to iterate over https://stackoverflow.com/questions/1303347/getting-a-map-to-return-a-list-in-python-3-x/1303354#1303354
y = list(map(lambda v: "%02d" %v, x))
print("y: ", repr(y))

Output:

Python 3 Python 2
Python 3.6.1 (default, Dec 2015, 13:05:11)
[GCC 4.8.2] on linux
   
x:  [1, 2, 3, 4, 5, 11]
y:  ['01', '02', '03', '04', '05', '11']
y:  ['01', '02', '03', '04', '05', '11']
y:  ['01', '02', '03', '04', '05', '11']
y:  ['01', '02', '03', '04', '05', '11']
y:  ['01', '02', '03', '04', '05', '11']
y:  <map object at 0x7fe1218200b8>
y:  ['01', '02', '03', '04', '05', '11']
Python 2.7.10 (default, Jul 14 2015, 19:46:27)
[GCC 4.8.2] on linux
   
('x: ', '[1, 2, 3, 4, 5, 11]')
('y: ', "['01', '02', '03', '04', '05', '11']")
('y: ', "['01', '02', '03', '04', '05', '11']")
('y: ', "['01', '02', '03', '04', '05', '11']")
('y: ', "['01', '02', '03', '04', '05', '11']")
('y: ', "['01', '02', '03', '04', '05', '11']")
('y: ', "['01', '02', '03', '04', '05', '11']")
('y: ', "['01', '02', '03', '04', '05', '11']")

–jeroen

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Posted in Conference Topics, Conferences, Development, Event, Python, Scripting, Software Development | Leave a Comment »

TFreedObject in FastMM4/FastMM4.pas at master · pleriche/FastMM4 · GitHub

Posted by jpluimers on 2020/01/08

Reminder to Self:

  {The class used to catch attempts to execute a virtual method of a freed
   object}
  TFreedObject = class
  public
    procedure GetVirtualMethodIndex;
    procedure VirtualMethodError;
{$ifdef CatchUseOfFreedInterfaces}
    procedure InterfaceError;
{$endif}
  end;

If you encounter the class TFreedObject when doing a cast, then you’re working on a freed object and have FastMM4 enabled to detect that.

Source: [WayBackFastMM4/FastMM4.pas at master · pleriche/FastMM4 · GitHub; FastMM4 – A memory manager for Delphi and C++ Builder with powerful debugging facilities

Note that if you want to see the underlying FastMM data for any TObject allocation, use this watch (where Self is the current instance):

PFullDebugBlockHeader(PByte(Self) - SizeOf(TFullDebugBlockHeader))^

You can also put a ,r behind it to see the fields of this structure:

(Reserved1:nil; Reserved2:nil; AllocatedByRoutine:$41BF74; AllocationGroup:0; 
AllocationNumber:592682; 
AllocationStackTrace:(4224198, 4233131, 4235210, 11103806, 6552132, 131126, 6597961, 11106984, 4235210, 11107153, 11104090); 
AllocatedByThread:90428; FreedByThread:90428; 
FreeStackTrace:(4241541, 131126, 4235210, 11103806, 6552132, 131126, 6597961, 11106984, 4235210, 11107153, 11104090); 
UserSize:36; PreviouslyUsedByClass:132272; HeaderCheckSum:2673350594)

–jeroen

Posted in Conference Topics, Conferences, Delphi, Development, Event, Software Development | Leave a Comment »

Crosscompiling with Lazarus 1.8 on Linux Mint 18.3 | The Programming Works

Posted by jpluimers on 2020/01/08

As I will likely need this one day: [Archive.is / WayBackCrosscompiling with Lazarus 1.8 on Linux Mint 18.3 | The Programming Works.

There are quite a few one-time manual setups to initially set this up, but after that it’s a piece of cake.

via:

–jeroen

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Posted in Development, FreePascal, Lazarus, Pascal, Software Development | Leave a Comment »

 
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