Board.fen() didn't update when ep_square is updated

[winapiadmin]

winapiadmin@ubuntu:~/venv/bin$ source activate
(venv) winapiadmin@ubuntu:~/venv/bin$ python
Python 3.12.3 (main, Nov  6 2024, 18:32:19) [GCC 13.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import chess
>>> chess.Board()
Board('rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1')
>>> x=chess.Board()
>>> x.push_san("e4")
Move.from_uci('e2e4')
>>> x
Board('rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR b KQkq - 0 1')
>>> x.ep_square
20
>>> x.push_san("e5")
Move.from_uci('e7e5')
>>> x
Board('rnbqkbnr/pppp1ppp/8/4p3/4P3/8/PPPP1PPP/RNBQKBNR w KQkq - 0 2')

OS:

(venv) winapiadmin@ubuntu:~/venv/bin$ neofetch
           `-mddhhhhhhhhhddmss`             winapiadmin@ubuntu 
        ./mdhhhhhhhhhhhhhhhhhhhhhh.         ------------------ 
     :mdhhhhhhhhhhhhhhhhhhhhhhhhhhhm`       OS: Lubuntu 24.04.1 LTS x86_64 
   :ymhhhhhhhhhhhhhhhyyyyyyhhhhhhhhhy:      Kernel: 6.13.0-061300rc1-generic 
  `odhyyyhhhhhhhhhy+-````./syhhhhhhhho`     Uptime: 50 mins 
 `hhy..:oyhhhhhhhy-`:osso/..:/++oosyyyh`    Packages: 2235 (dpkg), 13 (snap) 
 dhhs   .-/syhhhhs`shhhhhhyyyyyyyyyyyyhs    Shell: bash 5.2.21 
:hhhy`  yso/:+syhy/yhhhhhshhhhhhhhhhhhhh:   Resolution: 1440x900 
hhhhho. +hhhys++oyyyhhhhh-yhhhhhhhhhhhhhs   DE: LXQt 1.4.0 
hhhhhhs-`/syhhhhyssyyhhhh:-yhhhhhhhhhhhhh   WM: Openbox 
hhhhhhs  `:/+ossyyhyyhhhhs -yhhhhhhhhhhhh   Theme: Breeze [GTK3] 
hhhhhhy/ `syyyssyyyyhhhhhh: :yhhhhhhhhhhs   Icons: ePapirus [GTK3] 
:hhhhhhyo:-/osyhhhhhhhhhhho  ohhhhhhhhhh:   Terminal: qterminal 
 sdhhhhhhhyyssyyhhhhhhhhhhh+  +hhhhhhhhs    Terminal Font: Ubuntu Mono 14                                                       
 `shhhhhhhhhhhhhhhhhhhhhhy+` .yhhhhhhhh`    CPU: Intel i3-2100 (4) @ 3.100GHz                                                   
  +sdhhhhhhhhhhhhhhhhhyo/. `/yhhhhhhhd`     GPU: Intel 2nd Generation Core Processor Family                                     
   `:shhhhhhhhhh+---..``.:+yyhhhhhhh:       Memory: 1667MiB / 3367MiB                                                           
     `:mdhhhhhh/.syssyyyyhhhhhhhd:`                                                                                             
        `+smdhhh+shhhhhhhhhhhhdm`                                                                                               
           `sNmdddhhhhhhhddm-`                                                                                                  

Edit: hard-coded FEN generation without EPD is working:

winapiadmin@ubuntu:~/venv/bin$ source activate
(venv) winapiadmin@ubuntu:~/venv/bin$ python
Python 3.12.3 (main, Nov  6 2024, 18:32:19) [GCC 13.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import chess
>>> chess.Board()
Board('rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1')
>>> x=chess.Board()
>>> x.push_san("e4")
Move.from_uci('e2e4')
>>> f"{x.board_fen()} {"w" if x.turn else "b"} {x.castling_xfen()} {chess.square_name(x.ep_square) if x.ep_square else "-"} {x.halfmove_clock} {x.fullmove_number}"
'rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR b KQkq e3 0 1'

[niklasf]

Hi. There are multiple standards for en passant in FENs. See https://python-chess.readthedocs.io/en/latest/core.html#chess.Board.fen:

board.fen(..., en_passant: Literal['legal', 'fen', 'xfen'] = 'legal')

By default, only fully legal en passant squares are included (has_legal_en_passant()). Pass fen to strictly follow the FEN specification (always include the en passant square after a two-step pawn move) or xfen to follow the X-FEN specification (has_pseudo_legal_en_passant()).

[winapiadmin]

It should by default follows FEN specifications

---

From: Niklas Fiekas @.> Sent: Sunday, January 19, 2025 9:20 PM To: niklasf/python-chess @.> Cc: winapiadmin @.>; Author @.> Subject: Re: [niklasf/python-chess] Board.fen() didn't update when ep_square is updated (Issue #1134)

Hi. There are multiple standards for en passant in FENs. See https://python-chess.readthedocs.io/en/latest/core.html#chess.Board.fen:

board.fen(..., en_passant: Literal['legal', 'fen', 'xfen'] = 'legal')

By default, only fully legal en passant squares are included (has_legal_en_passant()https://python-chess.readthedocs.io/en/latest/core.html#chess.Board.has_legal_en_passant). Pass fen to strictly follow the FEN specification (always include the en passant square after a two-step pawn move) or xfen to follow the X-FEN specification (has_pseudo_legal_en_passant()https://python-chess.readthedocs.io/en/latest/core.html#chess.Board.has_pseudo_legal_en_passant).

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