PromptPlus

# PromptPlus ## **Calendar — Methods** [](https://www.nuget.org/packages/PromptPlus) [](https://opensource.org/licenses/MIT) [](https://dotnet.microsoft.com/)

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Every fluent method on ICalendarControl. Each returns the same control instance, so calls chain in any order. Call Run last.

The factory is PromptPlus.Controls.Calendar(string prompt = "", string? description = null), which returns ICalendarControl.

Quick jump: Layout · Culture · FirstDayOfWeek · Range · DisableDates · DisabledWeekend · AddNote · AddNotes · PageSize · Highlights · Interaction · InteractionAsync · Default · PredicateSelected · PredicateSelectedAsync · ChangeDescription · ChangeDescriptionAsync · EnableHistory · Styles · Options · Run

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Layout & culture

Layout

ICalendarControl Layout(CalendarLayout layout = CalendarLayout.SingleGrid)

Sets how the grid and its lines are drawn.

CalendarLayout	Renders
SingleGrid	Single-line box drawing (default)
DoubleGrid	Double-line box drawing
AsciiSingleGrid	ASCII single-line grid (portable, no Unicode)
AsciiDoubleGrid	ASCII double-line grid

PromptPlus.Controls.Calendar("Date")
    .Layout(CalendarLayout.AsciiSingleGrid)
    .Run();

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Culture

ICalendarControl Culture(CultureInfo culture)
ICalendarControl Culture(string cultureName)

Sets the culture used to display month names, day names, and date formatting — and to parse and validate dates. The default is the current PromptPlus culture. The string overload is shorthand for Culture(new CultureInfo(cultureName)).

using PromptPlusLibrary;
using System.Globalization;

PromptPlus.Controls.Calendar("Data")
    .Culture("pt-BR")
    .Run();

PromptPlus.Controls.Calendar("Date")
    .Culture(new CultureInfo("en-US"))
    .Run();

Culture(CultureInfo) throws ArgumentNullException if culture is null; Culture(string) throws ArgumentException if cultureName is null or empty.

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FirstDayOfWeek

ICalendarControl FirstDayOfWeek(DayOfWeek firstDayOfWeek)

Sets which weekday appears in the first column. When not set, defaults to PromptPlus.Config.FirstDayOfWeek (DayOfWeek.Sunday unless you’ve changed it globally) — not the active culture’s own first-day-of-week convention.

using PromptPlusLibrary;
using System;

PromptPlus.Controls.Calendar("Date")
    .FirstDayOfWeek(DayOfWeek.Monday)
    .Run();

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Restricting dates

Range

ICalendarControl Range(DateTime minValue, DateTime maxValue)

Defines an inclusive window of selectable dates. Days outside it are shown but cannot be confirmed.

using PromptPlusLibrary;
using System;

var today = DateTime.Now.Date;
PromptPlus.Controls.Calendar("Date")
    .Range(today.AddDays(-3), today.AddDays(3))
    .Run();

Throws ArgumentOutOfRangeException if minValue is greater than maxValue. A Default outside the range is ignored.

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DisableDates

ICalendarControl DisableDates(params DateTime[] dates)

Marks specific dates as non-selectable (rendered with the Disabled style).

using PromptPlusLibrary;
using System;

var today = DateTime.Now.Date;
PromptPlus.Controls.Calendar("Date")
    .DisableDates(today.AddDays(1), today.AddDays(2))
    .Run();

Throws ArgumentNullException if dates is null.

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DisabledWeekend

ICalendarControl DisabledWeekend(bool value = true)

Blocks Saturday and Sunday from selection. Default true when called.

PromptPlus.Controls.Calendar("Business date")
    .DisabledWeekend()
    .Run();

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Notes

AddNote

ICalendarControl AddNote(DateTime value, string? note = null)

Attaches a note to a single date. A null note becomes an empty string. Notes for the highlighted day are shown when the user presses F2 (see Operations).

using PromptPlusLibrary;
using System;

PromptPlus.Controls.Calendar("Date", "Press [F2] to read notes")
    .AddNote(DateTime.Now.Date, "Team standup at 09:00")
    .Run();

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AddNotes

ICalendarControl AddNotes((DateTime, string?)[] notes)

Adds several notes at once as (date, note) tuples. A null note becomes an empty string.

using PromptPlusLibrary;
using System;

var today = DateTime.Now.Date;
PromptPlus.Controls.Calendar("Date")
    .AddNotes(
    [
        (today.AddDays(1), "Tomorrow note"),
        (today.AddDays(2), "Day+2 note")
    ])
    .Run();

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PageSize

ICalendarControl PageSize(byte value)

Maximum number of notes shown per page (valid range 0–255). 0 (default) auto-computes from terminal height, reserving lines for header, footer, and pagination. Values above the available height are clamped.

PromptPlus.Controls.Calendar("Date").PageSize(3).Run();

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Highlights

Highlights

ICalendarControl Highlights(params DateTime[] dates)

Marks one or more dates so they stand out (rendered with the CalendarHighlight style). Highlighted dates remain selectable — the marking is purely visual.

using PromptPlusLibrary;
using System;

var today = DateTime.Now.Date;
PromptPlus.Controls.Calendar("Date")
    .Highlights(today, today.AddDays(3))
    .Run();

Throws ArgumentNullException if dates is null.

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Loading from a source

Interaction

ICalendarControl Interaction<T>(IEnumerable<T> items, Action<T, ICalendarControl> interactionAction)

Iterates a source collection and lets you configure the calendar programmatically per item — useful for generating notes from data.

using PromptPlusLibrary;
using System;

var today = DateTime.Now.Date;
PromptPlus.Controls.Calendar("Date")
    .Interaction(myEvents, (evt, ctrl) => ctrl.AddNote(evt.Date, evt.Title))
    .Run();

Throws ArgumentNullException if items or interactionAction is null.

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InteractionAsync

ICalendarControl InteractionAsync<T>(IEnumerable<T> items, Func<T, ICalendarControl, Task> interactionAction)

Asynchronous version of Interaction, for sources that need awaiting per item.

using PromptPlusLibrary;
using System;

var today = DateTime.Now.Date;
PromptPlus.Controls.Calendar("Date")
    .InteractionAsync([8, 9], async (offset, ctrl) =>
    {
        await Task.Delay(1).ConfigureAwait(false);
        ctrl.AddNote(today.AddDays(offset), $"Async note {offset}");
    })
    .Run();

Throws ArgumentNullException if items or interactionAction is null.

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Initial value

Default

ICalendarControl Default(DateTime value, bool useDefaultHistory = true)

Opens the grid on value (default is today). When useDefaultHistory is true and history is enabled, the last history value is preferred. A value outside the Range is ignored.

using PromptPlusLibrary;
using System;

PromptPlus.Controls.Calendar("Date")
    .Default(DateTime.Now)
    .Run();

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Validating the confirmed date

Validation runs on Enter. On failure the grid stays open and shows an error.

PredicateSelected

ICalendarControl PredicateSelected(Func<DateTime?, bool> isValidSelection)
ICalendarControl PredicateSelected(Func<DateTime?, (bool, string?)> validateSelection)

Overload	Return	Behavior
Func<DateTime?, bool>	true = valid	Generic error on failure
Func<DateTime?, (bool, string?)>	(isValid, message)	Custom message on failure

using PromptPlusLibrary;
using System;

// bool overload — only odd days allowed
PromptPlus.Controls.Calendar("Select odd day")
    .PredicateSelected(date => date.HasValue && date.Value.Day % 2 == 1)
    .Run();

// message overload — custom error text
PromptPlus.Controls.Calendar("Select day <= 28")
    .PredicateSelected(date =>
    {
        if (!date.HasValue)
            return (false, "Date is required");
        return date.Value.Day <= 28
            ? (true, (string?)null)
            : (false, "Only days up to 28 are allowed");
    })
    .Run();

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PredicateSelectedAsync

ICalendarControl PredicateSelectedAsync(Func<DateTime?, Task<bool>> isValidSelection)
ICalendarControl PredicateSelectedAsync(Func<DateTime?, Task<(bool, string?)>> validateSelection)

Asynchronous counterparts of PredicateSelected.

using PromptPlusLibrary;
using System;

var today = DateTime.Now.Date;
PromptPlus.Controls.Calendar("Select future date")
    .PredicateSelectedAsync(async date =>
    {
        await Task.Delay(1).ConfigureAwait(false);
        return date.HasValue && date.Value.Date >= today;
    })
    .Run();

⚠️ The async predicate is awaited synchronously (blocking) on the UI thread — keep it fast.

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Dynamic description

ChangeDescription

ICalendarControl ChangeDescription(Func<DateTime?, string> value)

Recomputes the description from the currently highlighted date as the user navigates.

using PromptPlusLibrary;
using System;

PromptPlus.Controls.Calendar("Date")
    .ChangeDescription(date => $"Selected day: {date:yyyy-MM-dd}")
    .Run();

Throws ArgumentNullException if value is null.

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ChangeDescriptionAsync

ICalendarControl ChangeDescriptionAsync(Func<DateTime?, Task<string>> value)

Asynchronous version of ChangeDescription.

using PromptPlusLibrary;
using System;

PromptPlus.Controls.Calendar("Date")
    .ChangeDescriptionAsync(date => Task.FromResult($"Async: {date:dddd, dd MMM yyyy}"))
    .Run();

Throws ArgumentNullException if value is null.

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History

EnableHistory

ICalendarControl EnableHistory(string filename, Action<IHistoryOptions>? options = null)

Persists confirmed dates to filename and can pre-select the last one (via Default(..., useDefaultHistory: true)). The IHistoryOptions builder is identical to the one documented for Input → EnableHistory (MinPrefixLength, MaxItems, ExpirationTime, FilterType, PageSize).

using PromptPlusLibrary;
using System;

PromptPlus.Controls.Calendar("Date")
    .Default(DateTime.Now, useDefaultHistory: true)
    .EnableHistory("calendar-history", opt => opt.MaxItems(5))
    .Run();

Throws ArgumentNullException if filename is null.

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Appearance & behavior

Styles

ICalendarControl Styles(CalendarStyles styleType, Style style)

Recolors one visual region of this control. See the region list and examples on the Styles page.

using PromptPlusLibrary;
using ConsolePlusLibrary;   // Color, Style live here

PromptPlus.Controls.Calendar("Date")
    .Styles(CalendarStyles.Selected, new Style(Color.Green, Color.Default))
    .Run();

Throws ArgumentNullException if style is null.

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Options

ICalendarControl Options(Action<IControlOptions> options)

Overrides global behaviors for this one control (prompt/description text, abort key, tooltip, hide-after-finish). See Global Behaviors → Per-Control Override.

PromptPlus.Controls.Calendar("Date")
    .Options(opt =>
    {
        opt.Description("Custom options sample");
        opt.ShowTooltip(true);
        opt.EnabledAbortKey(true);
    })
    .Run();

Throws ArgumentNullException if options is null.

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Running the control

Run

ResultPrompt<DateTime?> Run(CancellationToken token = default)

Renders the grid and blocks until the user confirms (Enter) or aborts (Esc). Returns ResultPrompt<DateTime?> — the .Content is null when aborted.

var result = PromptPlus.Controls.Calendar("Date").Run();
if (!result.IsAborted && result.Content.HasValue)
    PromptPlus.Console.WriteLine(result.Content.Value.ToString("d"));

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See also

• Operations — how these methods behave at runtime
• Styles — the CalendarStyles regions
• Index — overview and method map

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