feat: trait-flash-loan-user.flash-loan-user-trait implements (execute (<ft-trait> uint (optional (buff 16))) (response bool uint))

[fiftyeightandeight]

Those contracts implementing trait-flash-loan-user (e.g. flash-loan-user-margin-usda-wbtc.clar) should then convert (optional (buff 16)) into uint using the following:

(define-read-only (buff-to-uint (bytes (buff 16)))
	(+
		(match (element-at bytes u0) byte (byte-to-uint byte) u0)
		(match (element-at bytes u1) byte (* (byte-to-uint byte) u256) u0)
		(match (element-at bytes u2) byte (* (byte-to-uint byte) u65536) u0)
		(match (element-at bytes u3) byte (* (byte-to-uint byte) u16777216) u0)
		(match (element-at bytes u4) byte (* (byte-to-uint byte) u4294967296) u0)
		(match (element-at bytes u5) byte (* (byte-to-uint byte) u1099511627776) u0)
		(match (element-at bytes u6) byte (* (byte-to-uint byte) u281474976710656) u0)
		(match (element-at bytes u7) byte (* (byte-to-uint byte) u72057594037927936) u0)
		(match (element-at bytes u8) byte (* (byte-to-uint byte) u18446744073709551616) u0)
		(match (element-at bytes u9) byte (* (byte-to-uint byte) u4722366482869645213696) u0)
		(match (element-at bytes u10) byte (* (byte-to-uint byte) u1208925819614629174706176) u0)
		(match (element-at bytes u11) byte (* (byte-to-uint byte) u309485009821345068724781056) u0)
		(match (element-at bytes u12) byte (* (byte-to-uint byte) u79228162514264337593543950336) u0)
		(match (element-at bytes u13) byte (* (byte-to-uint byte) u20282409603651670423947251286016) u0)
		(match (element-at bytes u14) byte (* (byte-to-uint byte) u5192296858534827628530496329220096) u0)
		(match (element-at bytes u15) byte (* (byte-to-uint byte) u1329227995784915872903807060280344576) u0)
	)
)

flash-loan of alex-vault also needs to be updated (to pass (optional (buff 16))).

We also need a util / function to convert uint into (buff 16).

[fiftyeightandeight]

(define-ready-only (uint-to-buff uint) should be implemented by reversing (buff-to-uint (bytes (buff 16)))

[SaadTahirTintash]

flash-loan of alex-vault also needs to be updated (to pass (optional (buff 16))).

According to this comment, I understand that we need to change the flash-loan in trait-vault.clar from (optional memo) to (optional uint). But while I was checking the test case Flash Loan: create margin trade, the flash-loan function call is passing expiry as an argument to the function call flash-loan which accepts memo: number.

My question is then, do we need to change this .trait-vault flash-loan function signature? If yes then we have to pass expiry as a buffer. If not then we have to convert memo (optional uint) to (buff 16) and pass it in flash-loan-user execute method in alex-vault.clar.