# अवस्था और डेटा प्रवाह

> CrossFly का अवस्था-दर्शन — कोई रिएक्टिव binding नहीं, कोई DI नहीं, अनिवार्य + स्पष्ट अमान्यीकरण।

Source: https://crossfly.dev/hi/docs/concepts/state-and-data-flow — CrossFly documentation. Full docs as one file: https://crossfly.dev/llms-full.txt

# अवस्था और डेटा प्रवाह

यहीं CrossFly Flutter, Compose, SwiftUI या React से आने वालों को सबसे ज़्यादा चौंकाता है। दो जानबूझकर की गई
अनुपस्थितियाँ:

- **कोई स्वचालित रिएक्टिव binding नहीं है।** न `setState`, न observables, न `@State`, न recomposition। मॉडल
  बदलना UI को स्वयं अपडेट **नहीं** करता।
- **कोई dependency injection कंटेनर नहीं है।** न Dagger/Guice/Spring। आप अपनी निर्भरताएँ हाथ से बनाते और
  पास करते हैं (आमतौर पर स्क्रीन के कंस्ट्रक्टर के ज़रिए)।

## मॉडल: अनिवार्य + स्पष्ट अमान्यीकरण
आप **मॉडल को पढ़ते/लिखते हैं**, **कंपोनेंट को सीधे अपडेट करते हैं** और फ्रेमवर्क **पुनः पेंट करता है**:
```java
model.nome = "Ana";
label.setText(model.nome);   // अधिकांश setters पहले से ही layout अमान्य कर repaint() को कॉल करते हैं
```
अधिकांश कंपोनेंट setters पहले से ही आपके लिए `repaint()` चालू करते हैं / layout को अमान्य करते हैं। याद रखने
योग्य एकमात्र नियम:

> **ऐसी अवस्था बदली जिसे फ्रेमवर्क नहीं जानता** (आपका कोई काउंटर, कोई गणना, `onPaint` में बनाया गया कोई फ़ील्ड)?
> **आप** `repaint()` को बुलाते हैं। (देखें [paint thread](/docs/concepts/the-paint-thread)।)

### क्लासिक प्रति-उदाहरण
```java
this.progresso = 0.7f;   // मैंने एक फ़ील्ड बदला जिसे केवल मेरा onPaint पढ़ता है…
// …और स्क्रीन नहीं बदलती। कमी है:
Component.repaint();      // ✔ अब अगला frame नए मान को दर्शाता है
```
"मैंने अवस्था बदली और स्क्रीन अपडेट नहीं हुई" लगभग हमेशा एक छूटा हुआ `repaint()` होता है।

## यह चुनाव क्यों
- **पूर्वानुमेयता:** प्रवाह रैखिक और दृश्यमान है — डेटा → setter → repaint → frame। डिबग करने के लिए न कोई
  जादुई recomposition है, न कोई छिपा रिएक्टिव चक्र।
- **शून्य जादू, कम लागत:** न कोई रिएक्टिव निर्भरता ग्राफ़, न कॉन्फ़िगर करने के लिए कोई DI फ्रेमवर्क।
- इसकी कीमत स्पष्टता है: **अवस्था प्रबंधित करना एप्लिकेशन की ज़िम्मेदारी है**, फ्रेमवर्क की नहीं।

## संचार के तंत्र जो फ्रेमवर्क प्रदान करता है
- **Callbacks / actions** — `onAction(...)`, कंस्ट्रक्टर से पास किए गए callbacks (देखें
  [मान लौटाना](/docs/ui/navigation/returning-results))।
- **अभिभावक/बच्चा पदानुक्रम** — कंपोनेंट के वृक्ष में नेविगेट करना।
- **`property(k, v)`** — प्रति कंपोनेंट "डेटा की थैली" (देखें [सब कुछ एक Component है](/docs/concepts/everything-is-a-component))।
- **वैश्विक अवस्था** — जब समझ में आए, तब साझा static फ़ील्ड/सेवाएँ।

## अनुशंसित पैटर्न
चूँकि फ्रेमवर्क केवल ब्लॉक देता है, संगठन का पैटर्न (प्रति स्क्रीन एक **ViewModel/controller** +
डेटा के लिए **repository**) एप्लिकेशन की परंपरा है — जो
[best-practices](/docs/best-practices) में प्रलेखित है। फ्रेमवर्क आर्किटेक्चर थोपता नहीं; वह
कंपोनेंट और setter→`repaint()` जोड़ी प्रदान करता है।

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center;"><span class="nodeLabel"><p>अगला फ्रेम</p></span></div></foreignObject></g></g></g></g></g><defs><filter id="my-svg-drop-shadow" height="130%" width="130%"><feDropShadow dx="4" dy="4" stdDeviation="0" flood-opacity="0.06" flood-color="var(--text-dim)"/></filter></defs><defs><filter id="my-svg-drop-shadow-small" height="150%" width="150%"><feDropShadow dx="2" dy="2" stdDeviation="0" flood-opacity="0.06" flood-color="var(--text-dim)"/></filter></defs><linearGradient id="my-svg-gradient" gradientUnits="objectBoundingBox" x1="0%" y1="0%" x2="100%" y2="0%"><stop offset="0%" stop-color="var(--border-strong)" stop-opacity="1"/><stop offset="100%" stop-color="hsl(0, 0%, 90%)" stop-opacity="1"/></linearGradient></svg>
</div>

## यह भी देखें
- संबंधित: [paint thread](/docs/concepts/the-paint-thread) · [app आर्किटेक्चर (best-practices)](/docs/best-practices)